collapseGroup

Collapses the specified group. This hides the group items.

Parameters

row String|Element|jQuery

A string, DOM element or jQuery object which represents the group table row. A string is treated as a jQuery selector.

Example - collapse the first group

<div id="grid"></div>
<script>
$("#grid").kendoGrid({
  columns: [
    { field: "productName" },
    { field: "category" }
  ],
  dataSource: {
    data: [
      { productName: "Tea", category: "Beverages" },
      { productName: "Coffee", category: "Beverages" },
      { productName: "Ham", category: "Food" },
      { productName: "Bread", category: "Food" }
    ],
    group: { field: "category" }
  },
  groupable: true
});
var grid = $("#grid").data("kendoGrid");
grid.collapseGroup(".k-grouping-row:contains(Beverages)");
</script>

How to collapse all Groups in Grid by Default you can find in this article.