In order to delete rows on the client in javascript you need to use the javascript function: igtbl_deleteRow(gridName,rowID). First, be sure to allow the deletion itself by setting the AllowDeleteDefault property in the DisplayLayout object or AllowDelete on the specific band.

The function needs to be passed the name of the grid and the ID of the row you want to delete.

The following sample Javascript code would delete all rows on the client in a function.

function delete() {
    //get the first row in the grid
    var row=igtbl_getRowById("UltraWebGrid1r_0");
    //delete the first row in the grid
    igtbl_deleteRow("UltraWebGrid1","UltraWebGrid1r_0");
    //create a counter for the row id
    var cnt=0;
    //create a loop, if the row has a next sibling then we need to delete it
    while(row.NextSibling!=null)
    {
        //increment the counter for the next rowID
        cnt+=1;
        //get the row current row using the name of the grid and the row number from our counter so we can check it for a sibling
        row=igtbl_getRowById("UltraWebGrid1r_"+cnt)
        //finally delete that row,
        igtbl_deleteRow("UltraWebGrid1","UltraWebGrid1r_"+cnt);
    }
}

All the selected rows within the grid can be deleted as well. For deleting selected rows, use the following function: igtbl_deleteSelRows(gridName).

igtbl_deleteSelRows("UltraWebGrid1");

ms-help://INFRAGISTICS_HELP/INFRAGISTICS_WEB/Infragistics.WebUI.UltraWebGrid.v3/Infragistics.WebUI.UltraWebGrid.v3/Delete_Rows_On_Client-Side.htm