unSelectAll Returns: void
Unselect all records from the grid.
Examples
  
  <button id="btnSelectAll">Select All</button>
 <button id="btnUnSelectAll">UnSelect All</button>
 <br/><br/>
 <table id="grid"></table>
 <script>
     var grid = $("#grid").grid({
         dataSource: "../Grid/GetPlayers",
         columns: [ { field: "ID" }, { field: "Name" }, { field: "PlaceOfBirth" } ],
         selectionMethod: "checkbox",
         selectionType: "multiple"
     });
     $("#btnSelectAll").on("click", function () {
         grid.selectAll();
     });
     $("#btnUnSelectAll").on("click", function () {
         grid.unSelectAll();
     });
 </script>