There's an article about it in the official FANDOM help wiki, but be warned. You can only change your name once, after that, you can't do it again.
Dun dun DUUUUUUUUUNN!
community.wikia.com/wiki/Help:Contents
This link should bring you to to the Community Central help page. scroll down until down until you see a link that says "How do I change my username?".