######pour pouvoir modifier /etc/pve/corosync.conf

1)
systemctl stop pve-cluster
systemctl stop corosync

2)
pmxcfs -l

3)
rm ou nano /etc/pve/corosync.conf

4)
killall pmxcfs
systemctl start pve-cluster
systemctl start corosync
################################
D'aprés la doc et aprés suppression node > authentification failed webui:

root@bull2:~# systemctl stop pve-cluster
root@bull2:~# systemctl stop corosync
root@bull2:~# pmxcfs -l
[main] notice: forcing local mode (although corosync.conf exists)
root@bull2:~# rm /etc/pve/corosync.conf
root@bull2:~# rm -r /etc/corosync/*
root@bull2:~# killall pmxcfs
root@bull2:~# systemctl start pve-cluster
root@bull2:~# 

##########
Re-add the node to the cluster to update the keys and then update the certs

pvecm add xxx.xxx.xxx.xxx -force
pvecm updatecerts