There is to my knowledge no way to change a member's user name with this software as there was on the old software in use when we sold the site.
If you wish to set up a new account you can do so without having to delete this old one. A lot of data found in your posts would be lost to delete the account. It might mess with the flow of threads started by both you and others.
If you want to set up a new account just do so.
You can't have same e-mail address on both however. If you have two addresses no problem. If not just make a minor alteration in the one in your current account and then use correct one in the new account you wish to establish or get another and have two valid addresses.
I won't delete the account and in so doing mess up the flow of info in threads you have posted to.