How to Hide DDT BRT Admin Menus

function plt_hide_webalchlab_ddt_brt_menus() {
	//Hide "DDT Brt".
	remove_menu_page('waDdtBrt_brt-ddt-generale');
	//Hide "DDT Brt → DDT Libero".
	remove_submenu_page('waDdtBrt_brt-ddt-generale', 'waDdtBrt_brt-ddt&order_id=libero');
	//Hide "DDT Brt → Mittenti".
	remove_submenu_page('waDdtBrt_brt-ddt-generale', 'waDdtBrt_brt-ddt-mittenti');
	//Hide "DDT Brt → Impostazioni".
	remove_submenu_page('waDdtBrt_brt-ddt-generale', 'waDdtBrt_brt-ddt-impostazioni');
}

add_action('admin_menu', 'plt_hide_webalchlab_ddt_brt_menus', 11);

Where do I put this code?