I created ui-grid that has three columns, by default, the column header have a 'v' shaped icon (marked in red circle in the image) :
Here the code and the plunker:
var app = angular.module('app', ['ngTouch', 'ui.grid', 'ui.grid.expandable', 'ui.grid.selection', 'ui.grid.pinning']);
app.controller('ThirdCtrl', ['$scope', '$http', '$log', function ($scope, $http, $log) {
      $scope.gridOptions = {
        expandableRowTemplate: 'expandableRowTemplate.html',
        expandableRowHeight: 150,
        onRegisterApi: function (gridApi) {
            gridApi.expandable.on.rowExpandedStateChanged($scope, function (row) {
                if (row.isExpanded) {
                  row.entity.subGridOptions = {
                    columnDefs: [
                    { name: 'name'},
                    { name: 'gender'},
                    { name: 'company'}
                  ]};
                  $http.get('https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/data/100.json')
                    .success(function(data) {
                      row.entity.subGridOptions.data = data;
                    });
                }
            });
        }
      }
      $scope.gridOptions.columnDefs = [
        { name: 'id', pinnedLeft:true },
        { name: 'name'},
        { name: 'age'},
        { name: 'address.city'}
      ];
      $http.get('https://cdn.rawgit.com/angular-ui/ui-grid.info/gh-pages/data/500_complex.json')
        .success(function(data) {
          $scope.gridOptions.data = data;
        });
    }]);.grid {
  width: 100%;
  height: 400px;
}<!doctype html>
<html ng-app="app">
  <head>
    <script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.3/angular.js"></script>
    <script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.3/angular-touch.js"></script>
    <script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.3/angular-animate.js"></script>
    <script src="http://ui-grid.info/docs/grunt-scripts/csv.js"></script>
    <script src="http://ui-grid.info/docs/grunt-scripts/pdfmake.js"></script>
    <script src="http://ui-grid.info/docs/grunt-scripts/vfs_fonts.js"></script>
    <script src="http://ui-grid.info/release/ui-grid.js"></script>
    <link rel="stylesheet" href="http://ui-grid.info/release/ui-grid.css" type="text/css">
    <link rel="stylesheet" href="main.css" type="text/css">
  </head>
  <body>
<div ng-controller="ThirdCtrl">
   <div ui-grid="gridOptions" ui-grid-expandable class="grid"></div>
</div>
    <script src="app.js"></script>
  </body>
</html>In the image above the grid I have created in my project.
My question is how can I remove the "v" sign in header row in red circle?

 
     
     
     
     
     
    