How to Hide XML Gallery Admin Menus

function plt_hide_xml_gallery_menus() {
	//Hide "Gallery".
	remove_menu_page('xml-gallery/xml-gallery.php');
	//Hide "Gallery → Insert New Iten".
	remove_submenu_page('xml-gallery/xml-gallery.php', 'xml-gallery/xml-gallery.php');
	//Hide "Gallery → List items".
	remove_submenu_page('xml-gallery/xml-gallery.php', 'Listar items');
	//Hide "Gallery → Options".
	remove_submenu_page('xml-gallery/xml-gallery.php', 'Options');
}

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

Where do I put this code?