How to Hide Shorturl to random url Admin Menus

function plt_hide_shorturl_to_random_url_menus() {
	//Hide "URL shorter".
	remove_menu_page('url_shorter');

	//Hide "URL shorter".
	remove_menu_page('edit.php?post_type=url_shorter');
	//Hide "URL shorter → URL shorter".
	remove_submenu_page('edit.php?post_type=url_shorter', 'edit.php?post_type=url_shorter');
	//Hide "URL shorter → Add New Post".
	remove_submenu_page('edit.php?post_type=url_shorter', 'post-new.php?post_type=url_shorter');
}

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

Where do I put this code?