If you are selling secondhand you may delete the hardware serial from your SSL account.
If you have purchased second-hand you may contact the seller to transfer SSL plugin iLok licences to your iLok User ID directly and pay iLok's transfer fee. Here are iLok transfer instructions.
Please note the Production Pack bundled with hardware is non-transferrable, even if the unit was bought from an official music shop.
SSL is not able to transfer software for secondhand units nor revoke any activated iLok licences.
Regarding UC1 please see Secondhand UC1.