Karen, I don't understand. You are the one who originally created the unmerged match between them. When it was converted to a proposed merge, you would have had 30 days to accept or reject it before default approval was given for it to proceed. Why are you now saying that it was incorrect to have been done?
Unfortunately, Eddie is correct - there is no way to undo a merge once it has been completed. That's why there is a 30 day waiting period to allow both profile managers to determine for sure whether it is correct. The only thing that can be done now is, as Eddie said, to add a new profile with the information for the one who is no longer here. You can recover that information on the change pages.