in VHA, all Restricted Free Agents (RFA) automatically sign a Qualifying Offer (QO) since there are no hostile Offer Sheets permitted.
Having said this, if you wish to release your RFAs, you can do so as long as they have not signed their deal in real life.
So, bottom line, if your RFA is still unsigned in real life, you can mail the admins to release him in VHA.
Otherwise, you will retain his rights by default.
Remember that there is a Minor league minimum, so purge wisely