How to Hide the "Quick Multilingual" Admin Menu

function plt_hide_quick_multilingual_menus() {
	//Hide the "Settings → Quick Multilingual" menu.
	remove_submenu_page('options-general.php', 'quick-multilingual');
}

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

Where do I put this code?