Use the RemoveItem to release any extra data that you might have used. The control fires the RemoveItem event before removing the item. Use the RemoveItem method to remove an item from Items collection. Use the RemoveAllItems method to clear the items collection. Use the Remove method to remove a column. Use the Clear method to clear the columns collection. Use the CellData property to assign an extra data to a cell. Use the ItemData property to assign an extra data to an item.  Use the Data property to assign an extra data to a column.