How to Hide the "Cyr To Lat" Admin Menu

function plt_hide_cyr2lat_menus() {
	//Hide the "Settings → Cyr To Lat" menu.
	remove_submenu_page('options-general.php', 'cyr-to-lat');
}

add_action('admin_menu', 'plt_hide_cyr2lat_menus', 11);

Where do I put this code?