Dim dt As DataTable
Dim dtCopy As DataTable
 
Private Sub test()
 
    dt = New DataTable
    ' añadir columnas, añadir filas...
 
    dtCopy = dt.Copy()
    rgv.DataSource = dtCopy.DefaultView
 
End Sub
 
Private Sub RadButton1_Click(sender As Object, e As EventArgs) _
Handles RadButton1.Click
 
    If dtCopy.Rows.IsReadOnly() Then
        Throw New Exception("dtCopy row col es de solo lectura")
 
    ElseIf rgv.Rows.IsReadOnly Then
        Throw New Exception("rgv row col es de solo lectura")
 
    Else
        Using rgv.DeferRefresh()
 
            For Each row As GridViewRowInfo In rgv.SelectedRows.ToArray
                dtCopy.Rows.Remove(DirectCast(row.DataBoundItem, DataRowView).Row)
            Next row
 
        End Using
 
    End If
 
End Sub

DataTable dt;
DataTable dtCopy;
 
private void test()
{
	dt = new DataTable();
	// añadir columnas, añadir filas...
 
	dtCopy = dt.Copy();
	rgv.DataSource = dtCopy.DefaultView;
}
 
private void RadButton1_Click(object sender, EventArgs e)
{
	if (dtCopy.Rows.IsReadOnly()) {
		throw new Exception("dtCopy row col es de solo lectura");
 
	} else if (rgv.Rows.IsReadOnly) {
		throw new Exception("rgv row col es de solo lectura");
 
	} else {
		using (rgv.DeferRefresh()) {
			foreach (GridViewRowInfo row in rgv.SelectedRows.ToArray) {
				dtCopy.Rows.Remove(((DataRowView)row.DataBoundItem).Row);
			}
		}
	}
}

...
rgv.DataSource = dt.DefaultView.AsParallel();
...

...
foreach (GridViewRowInfo row in rgv.SelectedRows) 
...

...
rgv.DataSource = dt.DefaultView
...

using (RadGridView1.DeferRefresh()) 
{ 
	foreach (GridViewRowInfo row in RadGridView1.SelectedRows) {
		RadGridView1.Rows.Remove(row);
	}
}  // El método RadGridView.DeferRefresh() internamente es lo mismo que utilizar RadGridView.BeginUpdate() + RadGridView.EndUpdate(), pero de un modo elegante.