The intention of the options you see is that you would restore the required prior version, rather than just deleting the current version.
When a prior version is restored, it will gain the latest version number, and in version history, that version of the document that you originally wanted to delete will now have a delete option in it's action menu.
It's a little roundabout, but it does what you want without uploading any dummy versions.
Jamie McAllister
Consultant
Northridge Solutions Ltd
http://www.linkedin.com/in/jamiemcallister