My understanding is that complete removal of the post is not possible as the whole business of topic threading is dependant on the node for the original post being in place. If it is not there then any following replies must all disappear as well.
I guess it is possible for you to edit the macro that places the "deleted by author" text so the post just shows blank. Search for the macro "message_as_html".
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.