How to Hide the "Google API KEY" Admin Menu

function plt_hide_api_key_for_google_maps_menus() {
	//Hide the "Settings → Google API KEY" menu.
	remove_submenu_page('options-general.php', 'gmaps-api-key');
}

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

Where do I put this code?