Ah, I see - yes, this was before my time. We have actually been looking at being able to change names recently but from a technical point of view it is very difficult to change usernames because of where and how they appear in our database (I'm not aware of the exact details of this - I leave it to the technical gnomes). I know this sounds odd because we have changed usernames in the past, but that wasn't an ideal solution and didn't change usernames everywhere (in links to people's profiles, for example) so if we did it, we wouldn't be doing it in the same way we did before. So at the moment this isn't something we can offer, even if people only want to change their names to lower case - apologies for this.
THECORBYLOON, an email address cannot be associated with more than one account, so if you deactivate and try to sign up with a new account with the same email address, it won't work. However, you can send me an email and ask me to edit the email address in your old account so that you can then reuse it when creating a new account.
If anyone is thinking about deactivating and creating a new account, please consider that we cannot transfer any profile details, questions, answers and so on from one account to another - you'll be completely starting from scratch. Also, if your new username is completely different to your old one, bear in mind that people might not recognise you so this could cause confusion.