rbenjamin, If you are not requiring to transfer the meetings/recordings, etc from this user to another user, and are only seeking to transfer the license. I would go into the User Management section, Search for this user and update their license type to Basic.* Then search/add the new user as a licensed type to replace this one.
* Check box beside users name Select License and License Type Choose Basic
Rachel, I would suggest either, deactivating their account from the Users Management page, or if you open up their profile page as an admin, you can reset their password under the SignIn Section to another password.