[AccessD] Reset OrderBy

I'm using a simple procedure to set a form's OrderBy property. When I close
the form, I want to delete any setting, so that the property isn't saved
with the form. How can I do that? I tried 

Private Sub Form_Close()
  'Reset Order By property
  Me.OrderBy = ""
End Sub

But it doesn't work. Checked Help but didn't find anything helpful. I don't
really want to set the sort order to "" -- I just want to wipe it clean. My
guess is the property doesn't recognize "", although it doesn't error. 

Susan H.