From a 3PAR view you'd just take the Host out of the Host Set.
From a HyperV view... no idea, guessing Host needs to be removed from a cluster or set to some sort of maintenance mode.
Obviously this will remove ALL Volumes from the Host that it sees via the Host Set.
We do this a lot with VMware clusters, add new Hosts to the Host Set, migrate all VMs to the new Hosts, remove old Hosts from the cluster and then remove old Hosts from the Host Set.
You can't take some Volumes away from some Hosts if using Sets, you could take the Host down, remove it and then export everything other then the one Volume direct to the Host and bring it back but if the Host is in a cluster something may mushroom.