'deleting replies requires more explanation than the admin might like. I would suggest something like "This post was deleted because it was a response to a post that no longer exists." '
As a volunteer admin myself (i.e., no pay and yes, I work on weekends), I'd be happy to do this. But at first look, it seems the best way would be to edit the box the original reply was in; however, only the original poster can edit the message box. The only things an admin can edit are the subject line and surname boxes. If anyone sees a workaround, I'd be interested in hearing it. Fortunately, it's something I'd have to do very rarely on my boards.