If you use your Microsoft Account to log into Surface Pro/RT tablet and want to change the email address used as the account in Windows 8, here is the tutorials on how to do that.
* First signed in to your Microsoft Account on the tablet or computer. From start screen, open Charms bar by swiping from the right side, and click/tap on “PC Settings”.
* Select “Users” option on the left side. Go to the right side, and you should see “More account settings online” link under your current account. Internet Explorer or other web browser will open a webpage.
* Click on the “Update email address” link under Account summary.
To create new one, click Create a new email address, type in a name, choose hotmail.com/live.com address, and then Save button.
To use existing valid email address, check “Use a different address” and enter your email address. Then go to check your email and confirm it.