You could wipe the phone completely unless you want to keep everything else on the phone untouched. Then I would recommend backing up your phone and wiping it and then restore it and when it asks you what you want to restore uncheck the address book box and that will do it. I don't know of any other way to do it, maybe someone else will have a better (faster) way to do it.
You don't need to wipe it to achieve that. Simply create a back up with the back up and restore tool in desktop manager. Then go into advanced under back up and restore to open the back up file you just created. Clear the address book, and restore the back up.
