If you ever need to change the email address linked to your account you can do so quickly via 'Your Profile' under the 'Edit Profile' settings.
Visit your profile, found by clicking 'View Profile'. Under the header 'Contact information' you will see your email address, you can change this to another valid email address.
From here, type in a new, Valid, email address and hit the save button. This will change the email address you have registered to Classlist to your new one. Make sure you remember your new email address when you need to log in.