collapseItem

Method which collapses the table row with index passed as an argument.

collapseItem(index)
index	Integer	The row corresponding to the index will be collapsed.

Example:

function CollapseFirstMasterTableViewItem() {
    $find("<%= RadGrid1.ClientID %>").get_masterTableView().collapseItem(0);
}
function CollapseFirstDetailTableFirstItem() {
    $find("<%= RadGrid1.Items[0].ChildItem.NestedTableViews[0].ClientID %>").collapseItem(0);
}