Disable Proxmox locked firewall

Boot the system in rescue mode
Mount the system haradisk

root@rescue:/mnt# sudo cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty]
md126 : active raid1 sda2[0] sdd2[3] sdc2[2] sdb2[1]
      20955136 blocks super 1.2 [4/4] [UUUU]

md127 : active raid1 sdc4[0] sdb4[3] sda4[2] sdd4[1]
      1931359232 blocks super 1.2 [4/4] [UUUU]
      bitmap: 0/15 pages [0KB], 65536KB chunk

unused devices: <none>
root@rescue:/mnt# mount /dev/md127 /mnt/tmp
mount: unknown filesystem type 'LVM2_member'
mkdir /mnt/tmp && mount /dev/md126 /mnt/tmp

#chroot
chroot /mnt/tmp # now we can run server commands

nano /etc/pve/firewall/cluster.fw
HTML:
[OPTIONS]

enable: 1

to

HTML:
[OPTIONS]

enable: 0

and reboot it in normal mode


###########################other way

systemctl disable pve-firewall
systemctl mask pve-firewall

should do the trick. then after rebooting and fixing your config,
Code:
systemctl unmask pve-firewall
systemctl enable pve-firewall
systemctl start pve-firewall

should return to the defaults again.