The Don is correct. For compliance reasons ans also Chain of Custody reasons any onbe who has been granted access to DA will always remain in DA as so any reference of any searches that were performed under that account can still be recalled.
The only way to remove them is to delete the Customer Database and create a new one which will give you a fresh start but it will also mean you will loose any trace of searches you have already created.
Also note that if you have any searches and any legal holds on those searches you first need to release the holds before deleting the database or else the items will always remain on hold because Legal Hold is also marked in the EV database as well as the DA databases
