How to Hide the "Youtube Subscribe Link Locker" Admin Menu

function plt_hide_yt_subscribe_link_locker_menus() {
	//Hide the "Settings → Youtube Subscribe Link Locker" menu.
	remove_submenu_page('options-general.php', 'ytsll_settings');
}

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

Where do I put this code?