Since my iptables keeps growing, listing the whole table can take more than a few minutes these days. I dug around and found a couple of options that will do the job faster:
iptables -D chainname -s theipaddress -j DROP
Alternately, you can list:
iptables -L -v --line-numbers
iptables -D chainname linenumber_of_IP_to_delete
This will make cleaning up the Fail2Ban tables a lot easier, especially if one of your users decides to ban himself and you have to sift through a ton of numbers to find his IP.