function plt_hide_wp_megamenu_menus() {
//Hide "WP Mega Menu".
remove_menu_page('wp_megamenu');
//Hide "WP Mega Menu → WP Mega Menu".
remove_submenu_page('wp_megamenu', 'wp_megamenu');
//Hide "WP Mega Menu → Themes".
remove_submenu_page('wp_megamenu', 'wp_megamenu_themes');
//Hide "WP Mega Menu → Go Premium".
remove_submenu_page('wp_megamenu', 'wpmm-go-premium');
}
add_action('admin_menu', 'plt_hide_wp_megamenu_menus', 503);