You should send an email to an site administrator asking how you would change your username. But why would you want to? You can post under an alias whenever you want and you can have a large number of alias'. The one suggestion that I make is that if you are going to challenge another poster concerning something that you do not agree with, post using your username because to do otherwise is the sign of a emotional coward, in my opinion. I will sometimes use an alias when I want to be nutty-funny and when I want to good naturedly rib another poster. Sometimes I will also use an alias when I do plain vanilla posts.