http://pve.proxmox.com/wiki/Proxmox_Cluster_File_System_(pmxcfs)

stop the cluster file system in /etc/pve/
# systemctl stop pve-cluster

start it again but forcing local mode
# pmxcfs -l

remove the cluster configuration
# rm /etc/pve/cluster.conf
# rm /etc/cluster/cluster.conf
# rm /var/lib/pve-cluster/corosync.authkey

stop the cluster file system again
# systemctl stop pve-cluster

restart PVE services (or reboot)
# systemctl start pve-cluster
# systemctl restart pvedaemon
# systemctl restart pveproxy
# systemctl restart pvestatd

=======移除node==============
經PVE03 執行pvecm delnode pve07
刪除 已重灌的pve07 節點，corosync.conf 內的node 資料已刪除
但gui上仍出現pve07 的資料
需手動進pve03 的shell，進入/etc/pve/nodes，rm -rf pve07
手動刪除pve07 的資料夾，再重整網頁gui，pve07即消失