Rebalance is not a simple delete and re-create action. Even the Desktops are non-persistent, there are persistent disks associated with it. like (Internal disk)
These carries data like domain membership trust and all. Therefore, without a shared datastore, preserving and migrating such internal disk is impossible (and prevented).
Now for you case, since it is floating desktops (non- persistent),
- De-select the datastore of the host to be patched by editing the pool.
- Logoff active sessions (if any) for the specific VMs / put the VM into maintenance mode.
- Delete Those specific VMs through *View administrator Pool Inventory*
- Configure back the datastore spec layout after patching host,
- And then increase the pool size to the desired numbers
