cancelUpdate

Method which cancels the update for the edited table row passed as an argument or the row corresponding to the index passed as an argument.

cancelUpdate(gridItem)or cancelUpdate(index)
gridItem	HTML row object -
The edited row that will be switched in non-editable mode.
index	Integer	The row corresponding to the index will be switched in non-editable mode.

Example:

function CancelUpdateForFirstItem() {
    var masterTable = $find("<%= RadGrid1.ClientID %>").get_masterTableView();
    masterTable.cancelUpdate(masterTable.get_dataItems()[0].get_element());
}