Bill,
Backup first. SO Admin | File | Connect | Database | Backup.
One of 2 ways. Either SO Admin | File | Connect | Query | New | type "Delete Item" and press F5 | this will delete all of the items in the items file. If you have setup and alias or supplier part numbers, this is probably _not_ the way to go. Otherwise you will have to delete the alias and supplier's re-order numbers too.
Otherwise create a new blank database for _everything_, as above except instead of Query, do a Database | Create | Next | give it a name | Next | Next | click on the magnifying glass | double click on DBFiles folder | Double on rmsdb.bck | Next | Finish. The File | Connect | type in the new database name | OK |File | Configuration | type the new database name again and test it. This will delete _everything_.