Thread:Noreplyz/@comment-31105329-20181020122630/@comment-5811199-20181020230100

Hmm, I'm not too sure. I think that they're asking for your FANDOM/Wikia account password, which you won't have as you're connected via Facebook.

The best way to rename, in this case, would be to go through their general support form, Staff should be able to help you out there.