Use the following procedure to delete a robot or robots when the media server is up and running.
Any drives that are configured as residing in a robot that you delete are changed to standalone drives.
Any media in the deleted robot is also moved to standalone. If the media is no longer usable or valid, delete it from the NetBackup configuration.
See Deleting a volume.
If the media server is down or the host has failed and cannot be recovered, you can delete its robots by using a different procedure.