Yes this is possible in your account settings.
To change your email simply follow the Account Settings link in the top right corner of the window after logging-in. Click on the My Preferences button and in the Personal Info. tab and click on the Edit button under the email information block to modify that information.
You are responsible for remembering your email id and password. We cannot retrieve this information for you.
You should NOT change your email by any other means (such as when upgrading or signing in) as this will create a NEW account. See this FAQ.