If it's because you dislike your account name: you've made one other post in this forum so far, so I don't think you'll be losing too much. Just make a new account and start fresh.
If it's because you would prefer that that name isn't associated with this forum: tough luck, sorry. As Lutpin said, you can *try* to get a name change approved but I doubt it'll go through; however, you can pay 50 BTC and get a VIP forum rank, and change your name through that... if you think that's worth it.