I wouldn't worry about it though. I think that pretty much most of Fanpop would prefer a different nama pengguna to the one they have now. I don't know that for a fact obviously, but I've come across a lot of peeople who want to change their username.
It's why so many people make new accounts, but I don't advise that anda do that. Because you'll only lose everything you've done and have to start over. And tbh, no one's that bothered about your username.
No anda can't change it. The only way to make a new nama pengguna is to make another Fanpop account. Now anda can padam the one that anda have, but that's something that anda probably don't wanna do. If I were anda I would.