To remove your ban in the channel you must be identified as an AOp and then type /chanserv unban #Channel-name and then re-join.

About getting back at him is not something I really want to help with since that is just making you as bad as him. I still advise you to talk to the founder of the channel about this operator who bans you.

The wheel of time turns. What was, what will be, and what is, may yet fall under the Shadow.