Turning off the firewall for FastPanel

FastPanel: A webserver panel that is loaded with all the usual, necessary and nice to have options.
Free for now. Recommended too, see https://fastpanel.direct.

So what to do when you’ve locked yourself out through its firewall?
For CentOS, FastPanel uses iptables, so assuming you’ve still access to some sort of shell, you do this:

iptables -F
to delete all existing rules, and

iptables -I INPUT -j ACCEPT
to allow all traffic.

So you can try again.