Good morning, @lbethany ...
If you are a Canvas administrator at your school, you can go to the account "Settings" page. On the "Settings" tab of the "Settings" page, scroll down to the section on "Features". There is a check-box option for "Users can delete their institution-assigned email address". If you make any changes to this page, make sure to scroll down to the bottom of the page to "Update Settings".
How do I set details for an account? - Instructure Community (canvaslms.com) -- See the section on "View Features" about half-way down the page.
I hope this will be of some help to you. Let Community members know if you have any other questions about this...thanks!