Your account is still newbie so it's okay to forget this account and do what you want. Just forget it and don't think it anymore. Anyways you can ask the admin to change your username or password then forget it. But I don't think if admin will do that since your account is not a high profile and also the rank is still newbie. But you can give a try if you want.
If the reason is something relates to privacy, it's severe concern and OP can send a request to theymos for possible consideration and help.
If the reason is not related to privacy, but something unimportant, OP can abandon this account and leave the forum or create a new account with a username he likes.
OP can change the account email to an address with forum domain, and abandon the account. Avoid using a random email address @gmail and similarly as someone in future can register an email address like that and has access to this account.
If you don't want to set an email address, use something like yourUserName@invalid.bitcointalk.org; don't use a random nonsense email like y@x.com, since somebody might create that domain/email.