Add this code into header.php of your child theme.

Please make all changes to the child theme files, and do not add the code directly to the theme files, otherwise after updating the theme your fixes will be lost

header.php

add_action( 'mfn_hook_top', 'gm_child_show_menu', 1 );

if ( ! function_exists( 'gm_child_show_menu' ) ) {
	function gm_child_show_menu() {
		if ( function_exists( 'groovy_menu' ) ) {
			groovy_menu();
		}
	}
}

BeTheme Child theme with Groovy Menu 

Note: You can find archive with Child Theme for BeTheme inside the plugin, please follow to Groovy Menu > Integration section to download it.

header.php

<?php
/**
 * The Header for our theme.
 *
 * @package Betheme
 * @author Muffin group
 * @link https://muffingroup.com
 */
?><!DOCTYPE html>
<?php
    if ($_GET && key_exists('mfn-rtl', $_GET)):
	echo '<html class="no-js" lang="ar" dir="rtl">';
    else:
?>
<html <?php language_attributes(); ?> class="no-js<?php echo esc_attr(mfn_user_os()); ?>"<?php mfn_tag_schema(); ?>>
<?php endif; ?>

<head>

<meta charset="<?php bloginfo('charset'); ?>" />
<?php wp_head(); ?>

</head>

<body <?php body_class(); ?>>

    <?php do_action('mfn_hook_top'); ?>

    <?php get_template_part('includes/header', 'sliding-area'); ?>

    <?php
	if (mfn_header_style(true) == 'header-creative') {
	    get_template_part('includes/header', 'creative');
	}
    ?>

    <div id="Wrapper">

	<?php

	    // featured image: parallax

	    $class = '';
	    $data_parallax = array();

	    if (mfn_opts_get('img-subheader-attachment') == 'parallax') {
		$class = 'bg-parallax';

		if (mfn_opts_get('parallax') == 'stellar') {
		    $data_parallax['key'] = 'data-stellar-background-ratio';
		    $data_parallax['value'] = '0.5';
		} else {
		    $data_parallax['key'] = 'data-enllax-ratio';
		    $data_parallax['value'] = '0.3';
		}
	    }
	?>

	<?php
	    if (mfn_header_style(true) == 'header-below') {
		echo mfn_slider();
	    }
	?>

	<div id="Header_wrapper" class="<?php echo esc_attr($class); ?>" <?php if ($data_parallax) {
	    printf('%s="%.1f"', $data_parallax['key'], $data_parallax['value']);
	} ?>>

	    <?php
		if ('mhb' == mfn_header_style()) {

		    // mfn_header action for header builder plugin

		    do_action('mfn_header');
		    echo mfn_slider();

		} else {

		    // EDITED: Remove header ----------------------------------------------------------- Begin

		    //echo '<header id="Header">';
			//if (mfn_header_style(true) != 'header-creative') {
			//    get_template_part('includes/header', 'top-area');
			//}
			//if (mfn_header_style(true) != 'header-below') {
			    echo mfn_slider();
			//}
			//echo '</header>';

			// EDITED: Remove header ----------------------------------------------------------- End

		}
	    ?>

	    <?php
		if ((mfn_opts_get('subheader') != 'all') &&
		    (! get_post_meta(mfn_ID(), 'mfn-post-hide-title', true)) &&
		    (get_post_meta(mfn_ID(), 'mfn-post-template', true) != 'intro')) {

		    $subheader_advanced = mfn_opts_get('subheader-advanced');

		    if (is_search()) {

			echo '<div id="Subheader">';
			    echo '<div class="container">';
				echo '<div class="column one">';

				    if (trim($_GET['s'])) {
					global $wp_query;
					$total_results = $wp_query->found_posts;
				    } else {
					$total_results = 0;
				    }

				    $translate['search-results'] = mfn_opts_get('translate') ? mfn_opts_get('translate-search-results', 'results found for:') : __('results found for:', 'betheme');
				    echo '<h1 class="title">'. esc_html($total_results) .' '. esc_html($translate['search-results']) .' '. esc_html($_GET['s']) .'</h1>';

				echo '</div>';
			    echo '</div>';
			echo '</div>';

		    } elseif (! mfn_slider_isset() || (is_array($subheader_advanced) && isset($subheader_advanced['slider-show']))) {

			// subheader

			$subheader_options = mfn_opts_get('subheader');

			if (is_home() && ! get_option('page_for_posts') && ! mfn_opts_get('blog-page')) {
			    $subheader_show = false;
			} elseif (is_array($subheader_options) && isset($subheader_options[ 'hide-subheader' ])) {
			    $subheader_show = false;
			} elseif (get_post_meta(mfn_ID(), 'mfn-post-hide-title', true)) {
			    $subheader_show = false;
			} else {
			    $subheader_show = true;
			}

			// title

			if (is_array($subheader_options) && isset($subheader_options[ 'hide-title' ])) {
			    $title_show = false;
			} else {
			    $title_show = true;
			}

			// breadcrumbs

			if (is_array($subheader_options) && isset($subheader_options[ 'hide-breadcrumbs' ])) {
			    $breadcrumbs_show = false;
			} else {
			    $breadcrumbs_show = true;
			}

			if (is_array($subheader_advanced) && isset($subheader_advanced[ 'breadcrumbs-link' ])) {
			    $breadcrumbs_link = 'has-link';
			} else {
			    $breadcrumbs_link = 'no-link';
			}

			// output

			if ($subheader_show) {

			    echo '<div id="Subheader">';
				echo '<div class="container">';
				    echo '<div class="column one">';

					if ($title_show) {
					    $title_tag = mfn_opts_get('subheader-title-tag', 'h1');
					    echo '<'. esc_attr($title_tag) .' class="title">'. wp_kses(mfn_page_title(), mfn_allowed_html()) .'</'. esc_attr($title_tag) .'>';
					}

					if ($breadcrumbs_show) {
					    mfn_breadcrumbs($breadcrumbs_link);
					}

				    echo '</div>';
				echo '</div>';
			    echo '</div>';

			}
		    }
		}
	    ?>

	</div>

	<?php
	    if (get_post_meta(mfn_ID(), 'mfn-post-template', true) == 'intro') {
		get_template_part('includes/header', 'single-intro');
	    }
	?>

	<?php do_action('mfn_hook_content_before');

header-shop.php

<?php
/**
 * The Header for our theme.
 *
 * @package Betheme
 * @author Muffin group
 * @link https://muffingroup.com
 */
?><!DOCTYPE html>
<?php
	if ($_GET && key_exists('mfn-rtl', $_GET)):
		echo '<html class="no-js" lang="ar" dir="rtl">';
	else:
?>
<html <?php language_attributes(); ?> class="no-js<?php echo esc_attr(mfn_user_os()); ?>"<?php mfn_tag_schema(); ?>>
<?php endif; ?>

<head>

<meta charset="<?php bloginfo('charset'); ?>" />
<?php wp_head(); ?>

</head>

<body <?php body_class(); ?>>

	<?php do_action('mfn_hook_top'); ?>

	<?php get_template_part('includes/header', 'sliding-area'); ?>

	<?php
		if (mfn_header_style(true) == 'header-creative') {
			get_template_part('includes/header', 'creative');
		}
	?>

	<div id="Wrapper">

		<?php

			// featured image: parallax

			$class = '';
			$data_parallax = array();

			if (mfn_opts_get('img-subheader-attachment') == 'parallax') {
				$class = 'bg-parallax';

				if (mfn_opts_get('parallax') == 'stellar') {
					$data_parallax['key'] = 'data-stellar-background-ratio';
					$data_parallax['value'] = '0.5';
				} else {
					$data_parallax['key'] = 'data-enllax-ratio';
					$data_parallax['value'] = '0.3';
				}
			}
		?>

		<?php
			$shop_id = wc_get_page_id('shop');

			if (mfn_header_style(true) == 'header-below') {
				if (is_shop() || (mfn_opts_get('shop-slider') == 'all')) {
					echo mfn_slider($shop_id);
				}
			}
		?>

		<div id="Header_wrapper" class="<?php echo esc_attr($class); ?>" <?php if ($data_parallax) {
			printf('%s="%.1f"', $data_parallax['key'], $data_parallax['value']);
		} ?>>

			<?php
				if ('mhb' == mfn_header_style()) {

					// mfn_header action for header builder plugin

					do_action('mfn_header');
					if (is_shop() || (mfn_opts_get('shop-slider') == 'all')) {
						echo mfn_slider($shop_id);
					}

				} else {

					// EDITED: Remove header ----------------------------------------------------------- Begin

					//echo '<header id="Header">';
					//if (mfn_header_style(true) != 'header-creative') {
					//	get_template_part('includes/header', 'top-area');
					//}
					if (mfn_header_style(true) != 'header-below') {
						if (is_shop() || (mfn_opts_get('shop-slider') == 'all')) {
							echo mfn_slider($shop_id);
						}
					}
					//echo '</header>';

					// EDITED: Remove header ----------------------------------------------------------- End

				}
			?>

			<?php
				function mfn_woocommerce_show_page_title()
				{
					return false;
				}
				add_filter('woocommerce_show_page_title', 'mfn_woocommerce_show_page_title');

				$subheader_advanced = mfn_opts_get('subheader-advanced');

				if (! mfn_slider_isset($shop_id) || is_product() || (is_array($subheader_advanced) && isset($subheader_advanced['slider-show']))) {

					// subheader

					$subheader_options = mfn_opts_get('subheader');

					if (is_array($subheader_options) && isset($subheader_options['hide-subheader'])) {
						$subheader_show = false;
					} elseif (get_post_meta(mfn_ID(), 'mfn-post-hide-title', true)) {
						$subheader_show = false;
					} else {
						$subheader_show = true;
					}

					// title

					if (is_array($subheader_options) && isset($subheader_options[ 'hide-title' ])) {
						$title_show = false;
					} else {
						$title_show = true;
					}

					// breadcrumbs

					if (is_array($subheader_options) && isset($subheader_options['hide-breadcrumbs'])) {
						$breadcrumbs_show = false;
					} else {
						$breadcrumbs_show = true;
					}

					// output

					if ($subheader_show) {

						echo '<div id="Subheader">';
							echo '<div class="container">';
								echo '<div class="column one">';

									if ($title_show) {

										$title_tag = mfn_opts_get('subheader-title-tag', 'h1');

										// single product can not use H1
										if (is_product() && $title_tag == 'h1') {
											$title_tag = 'h2';
										}

										echo '<'. esc_attr($title_tag) .' class="title">';
											if (is_product() && mfn_opts_get('shop-product-title')) {
												the_title();
											} else {
												woocommerce_page_title();
											}
										echo '</'. esc_attr($title_tag) .'>';
									}

									if ($breadcrumbs_show) {
										$home = mfn_opts_get('translate') ? mfn_opts_get('translate-home', 'Home') : __('Home', 'betheme');
										$woo_crumbs_args = apply_filters('woocommerce_breadcrumb_defaults', array(
											'delimiter' => false,
											'wrap_before' => '<ul class="breadcrumbs woocommerce-breadcrumb">',
											'wrap_after' => '</ul>',
											'before' => '<li>',
											'after' => '<span><i class="icon-right-open"></i></span></li>',
											'home' => esc_html($home),
										));

										woocommerce_breadcrumb($woo_crumbs_args);
									}

								echo '</div>';
							echo '</div>';
						echo '</div>';
					}
				}
			?>

		</div>

		<?php do_action('mfn_hook_content_before');

functions.php

<?php
/**
 * Betheme Child Theme
 *
 * @package Betheme Child Theme
 * @author Muffin group
 * @link https://muffingroup.com
 */

/**
 * Child Theme constants
 * You can change below constants
 */

// white label

define('WHITE_LABEL', false);

/**
 * Enqueue Styles
 */

function mfnch_enqueue_styles()
{
	// enqueue the parent stylesheet
	// however we do not need this if it is empty
	// wp_enqueue_style('parent-style', get_template_directory_uri() .'/style.css');

	// enqueue the parent RTL stylesheet

	if (is_rtl()) {
		wp_enqueue_style('mfn-rtl', get_template_directory_uri() . '/rtl.css');
	}

	// enqueue the child stylesheet

	wp_dequeue_style('style');
	wp_enqueue_style('style', get_stylesheet_directory_uri() .'/style.css');
}
add_action('wp_enqueue_scripts', 'mfnch_enqueue_styles', 101);

/**
 * Load Textdomain
 */

function mfnch_textdomain()
{
	load_child_theme_textdomain('betheme', get_stylesheet_directory() . '/languages');
	load_child_theme_textdomain('mfn-opts', get_stylesheet_directory() . '/languages');
}
add_action('after_setup_theme', 'mfnch_textdomain');

// ----------------------------------------------------------
// -------- Add Groovy Menu integration function. -----------
// ----------------------------------------------------------
add_action( 'mfn_hook_top', 'gm_child_show_menu', 1 );

if ( ! function_exists( 'gm_child_show_menu' ) ) {
	function gm_child_show_menu() {
		if ( function_exists( 'groovy_menu' ) ) {
			groovy_menu();
		}
	}
}