Undo Method [Excel 2003 VBA Language Reference]
Cancels the last user-interface action.
expression Required. An expression that returns an Application object.
This method undoes only the last action taken by the user before running the macro, and it must be the first line in the macro. It cannot be used to undo Visual Basic commands.
This example cancels the last user-interface action. The example must be the first line in a macro.