I wanted to change my username but use the same email address but there is not settings that could do that so what I did was, I went to the my evernote home page, went to "Account Settings", then went to "Security", then went ahead and changed my current email address to a different one. Then, I made a new account using my old email address with the new username that I wanted and it allowed me to create a new account. So basically, in the end, I have 2 new accounts. One is linked to my original account, and the other one linked to a different account. I would just then deactivate that account and move my saved items over to my original account again.