It is possible to remove the latest version of the family table, the issue is that if any part is used in any model in windchill you will not be able to delete the items. PTC was unable to solve my issue with this and I ended up obseleting the parts and recreating them.
Based on my experience, if your Windchill admin, has a lot of experience you have a shot of saving the files, otherwise it will most likely be easier to just recreate them.