Clear custom field filter

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jsgrid/1.5.3/jsgrid.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jsgrid/1.5.3/jsgrid-theme.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/jsgrid/1.5.3/jsgrid.min.js"></script>
<div id="jsGrid"></div>

JavaScript

var users = ["John", "Jane", "Joe", "Jane"];

//userfield for user
var UserField = function (config) {
  jsGrid.Field.call(this, config);
};



  UserField.prototype = new jsGrid.Field({

      //properties
      editing: false,
      validate: "required",
      
      //templates
      insertTemplate: function (value) {
        return this._insertControl = $("<Input type ='text'>").autocomplete({
          source: users
        });
      },
      filterTemplate: function (value) {
        return this._filterControl = $("<Input type ='text'>").autocomplete({
          source: users
        });
      },
      insertValue: function () {
        return this.insertTemplate.val();
      },
      filterValue: function (val) {
      return 'Otto;'
       
      }   

  });

    //define
    jsGrid.fields.user = UserField;



var clients = [
        { "Name": "Otto Clay", "Age": 25, "Country": 1, "Address": "Ap #897-1459 Quam Avenue", "Married": false },
        { "Name": "Connor Johnston", "Age": 45, "Country": 2, "Address": "Ap #370-4647 Dis Av.", "Married": true },
        { "Name": "Lacey Hess", "Age": 29, "Country": 3, "Address": "Ap #365-8835 Integer St.", "Married": false },
        { "Name": "Timothy Henson", "Age": 56, "Country": 1, "Address": "911-5143 Luctus Ave", "Married": true },
        { "Name": "Ramona Benton", "Age": 32, "Country": 3, "Address": "Ap #614-689 Vehicula Street", "Married": false }
    ];


  var countries = [
    { Name: "", Id: 0 },
    { Name: "United States", Id: 1 },
    { Name: "Canada", Id: 2 },
    { Name: "United Kingdom", Id: 3 }
  ];

  $("#jsGrid").jsGrid({
    width: "100%",
    height: "400px",

    inserting: true,
    editing: true,
    filtering: true,
    sorting: true,
    paging: true,
	autoload: true,
    controller: {
                        loadData: function () {
                            return clients;
                        }
                    },

    fields: [
      { name: "Name", type: "text", width: 150,...