Thread:EthanConquistador/@comment-24182086-20140629220008/@comment-6812733-20140629221032

On Wikia, if your account is confirmed, you can change your username. This can be done once and only once. Before making an account rename request, make sure that the new name is in fact the one you want to be called, and that the username is not already taken. Once you have decided to change your name, send your rename request to Wikia Staff, who will then review the request to rename your account.

tl;dr You need to send rename request to the Wikia Staff and ask them to rename your account, but that can be done only once.