How to remove Proxmox VE node or nodes from cluster

It is possible to manually remove nodes from a cluster setup.

Run the following commands from each of the member servers:

systemctl stop pve-cluster corosync
pmxcfs -l
rm -rf /etc/corosync/*
rm /etc/pve/corosync.conf
killall pmxcfs
systemctl start pve-cluster

You may also need to manually remove cluster member config files at /etc/pve/nodes/. You should leave the directory with the name of the server you are on.