How to Hide the "Ergonet Varnish Cache" Admin Menu

function plt_hide_ergonet_varnish_cache_menus() {
	//Hide the "Settings → Ergonet Varnish Cache" menu.
	remove_submenu_page('options-general.php', 'varnishCacheInfo');
}

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

Where do I put this code?