On the student tab in MyCambrian, scroll to the Personal Checklist and click on Update/Change for the field you would like to edit.
It will bring you to this page
To add a new email, select the type of email address from the drop-down, Students select EDU Email (Student) and click on Submit
Enter the new email and click Submit
Go to your old preferred email
Deselect the Make this your Preferred address check mark and click Submit
Select the New email and then click the Make this your Preferred address check mark and click Submit again.
If you are trying to delete your email address, you first have to make a different email your primary.