can I change my username?

Yes, you can change your username.

Got to My Account (right hand column)

Click on Click here to edit personal data.....

Then change your name. 

Then press Save Changes. 

Ah, your user name, I get it now. Don't mind me, I'm a bit slow on the uptake.

I would imagine if you email POE (Chris), or Ron Brind, let them know you want your username changed, they will tell you if you can or can't.

Of course, Ron, Chirs or Sarah may very well see this post too, and come to the rescue.

Sorry I didn't read your first post properly, I just asumed (something I always tell people NOT to do) you wanted to change your display name.

Silly me!