Removing 3 nodes from 6 node cluster

I need to remove 3 nodes from a 6 node cluster and they are not coming back , the remaining 3 nodes will be gradually retiring after moving all the VMs. I have done that before few years ago with pvecm expected command. Is there any other way ? There will be no HA on remaining nodes , is expected 3 or 2 best for 3 nodes ?

Thank you