The question has been closed for the following reason "The question is answered, right answer was accepted" by DJ Scooby Doo Aug 25 '12 at 00:56
You can't. Once you make an account with Gmail, Yahoo, etc. You keep it forever. The only way to be guaranteed a change is if you own your own domain name. I suggest you make another email and set the old email to forward all your emails to the new one.
answered Aug 24 '12 at 21:54
DJ Scooby Doo
Or if it is with your internet service provide you most likely not able to either since some providers only give specific usernames for their emailing address that are being used as well. I used to work for Bell Canada and usernames for emailing address cannot be change. You could always ask to see if they can. But most likely not able to.
answered Aug 24 '12 at 22:34