To keep your anonymity the best choice you have is to start a new account. As others have stated you would have to donate 10 BTC in order to be able to do so.

If, what you're saying on these forums, will result in governmental blowback or perhaps losing a job then you absolutely must protect yourself and open an new account. (Don't use meepmeep as this post will link the two usernames together.)

If you want to change your username for marketing reasons -- ahhh, that's another story. You need to decide that.