If they were NEVER used before, then you could delete them from the IV00101 - IV00116 tables. They won't be in all of the tables, but those are the ones you need to check in. However, keep in mind that if you delete them directly from the table, there may be add-ins or other processes that may be affected. I don't recommend you do it this way. If you decide to move forward with a delete like this, make sure you back up your entire database before doing it in case something gets hosed. Also, run check links after the delete to check for errors.