If you purchased an Adobe Creative Cloud subscription prior to Duke entering into a license agreement with Adobe, you can cancel your subscription with Adobe to not be charged any more.
If you are an active student, you should already have an account. If you are faculty/staff, you will need to purchase and receive a license through OIT before you can cancel.
You will just need to contact Adobe and indicate that you now have a subscription through your school/employer. Your username is [netID]@duke.edu.
Adobe agents can use their tools to validate that the user has been added to the enterprise agreement and the individual subscription canceled without penalty if the user is on an annual plan.
For month-to-month subscriptions, the user can cancel themselves. https://helpx.adobe.com/support.html >>> Manage Creative Cloud membership