Contact theymos or cyrus but don't pester them about it if you don't get a response. They're more likely to grant requests like this that are only minor changes but it's not a priority for them.
Thanks for this info
I'm not sure why having your username in capitals is a big deal though. In fact, I'd say it's probably better in lowercase.
My username contains both Letters and Numbers and I think If I could Capitalize letters,it would be good.
I thought it wouldn't require much to do this apparently minor change but as you now informed,only theymos or cyrus can do it,and I don't want to encourage upon their precious time for such a petty thing,I am giving up on this idea