Cleanly remove appliance from NBU domain

Hello,

I need help to cleanly remove 5230 appliance configured as a media server from NBU domain.

Currently we have Windows based master server and 2 5230s as  media servers. One of the appliances is being used for backups and the other one strictly for duplications. I am trying to remove the second one and reconfigure it as a master in our DR site and use AIR for replication.

Thank you.