Completely remove ufw, delete all iptables chains and rules, for a fresh start with nftables firewall in Ubuntu MATE 19.04

[Jags]

@ugnvs

Well, just give it a try! Add any rule, reboot and verify if it was loaded ok again.

Just changed a rule in nftables.conf, restarted the nftables.service, and yes it's working.

Thank you