You can right click on the array and choose "Connectivity Status"   Then find the old physical server and expand to see the initiators.   Then Click each initiator and select Deregister.   You may need to be in engineering mode to do this.  I would also remove the zones for that host from the active zoneset.
Good Afternoon -  Fairly new to the EMC world, so please be gentle. I think I made a newbie mistake and cannot figure out what to do next.  P to V'd (vmware) a server that originally booted from SAN. I then went and 'cleaned' up the SAN by deleting the old physical servers remote mirror, consistency group, storage group and finally the LUN that it booted from.  I now receive an error in Navisphere that says...    HBA (20:00:00:E0:8B:09:7B:93:21:00:00:E0:8B:09:7B:93) on Host (server01.domain.COM(66d8d9ba-6535-4980-a1c3-9c623ffeb36d)) may not be connected to a storage group. This HBA is not able to access LUNs that belong to its server. Alert Code: 0x721b Resolution Manually register the initiator in Navisphere or stop I/O from the server and remove/re-add it to the storage group. See online help for guidance.  Normally, I would follow the suggested resolution however the old physical server is long gone.  I then realized that the now virtual server (that USED to be a physical server) had Navisphere and SanSurfer was still running on it and thought that might have been the issue however no dice, I uninstalled the software and the error remains.  How can I tell Navisphere that server01 no longer exists, to get rid of the error?   Thank you in advance for your help.  CX4 FLARE Code 29 Navisphere 6
How do I unregister an HBA after the storage group / host etc. has been deleted?