To remove a user's Alumni Affiliation so they may be re-enrolled:
  1. Naviate to: Core> People Finder
  2. Search for the Past Student by their last name and click on their name
  3. Click on the 'Access' tab for the user
  4. Click on Alumni Affiliation
  5. Click Edit for the Grad Year
  6. Select Delete
  7. Click Confirm

You will then be able to re-enroll the Past Student.