You can change your email address to a new one.
To do so, go to your profile, click "Account Related Settings" under "Modify Profile" at left side of the page and enter your new email address.
Once you change your email address, an email will be sent to your old email address.
How can the OP change it as long as he doesn't remember his current password. Any changes to
Account Related Settings require password when you want to save changes. OP should probably check if the browser he's using is set to offer password saving, if it hasn't then I think he needs to enable it. But about cases like this, I have no experience. There must be a way to save him.