When a row is removed, all data in that row is lost. You can also call the Delete method of the DataRow class to just mark a row for removal. Calling RemoveAt is the same as calling Delete and then calling AcceptChanges.
You can use the Clear method to remove all members of the collection at one time.
Dim table As DataTable = CType(DataGrid1.DataSource, DataTable)
Dim rowCollection As DataRowCollection = table.Rows
If rowCollection.Count = 0 ThenExitSubEndIf
rowCollection.RemoveAt(rowCollection.Count - 1)
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)