delete: function (delete_url, callback) {
        // send DELETE to a netdata registry:
        $.ajax({
            url: NETDATA.registry.server + '/api/v1/registry?action=delete&machine=' + NETDATA.registry.machine_guid + '&name=' + encodeURIComponent(NETDATA.registry.hostname) + '&url=' + encodeURIComponent(NETDATA.serverDefault) + '&delete_url=' + encodeURIComponent(delete_url),
            async: true,