Lets face it, 9 out of 10 times if you are removing an IP address from fail2ban, it is probably your own. I have locked myself out remotely from my own server at a remote location more than once. This is why you always have several methods of getting back into your own box.
First things first, lets look at iptables and get an idea of the jail names.
Looking at the bottom of this picture you will see where I have a host jailed from failed logins. Now we need to get the actual jail name.
We will remove this host in the next step.
That is all to it, if we run the same command again we will see the number in the jail down to one.