How to Hide WP Mega Menu Admin Menus

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);

Where do I put this code?