As a Platform Manager: 
  1. Navigate to Core.
  2. Select Users/Access > Profile.
  3. Click Manage Student Enrollments.
  4. To the right of your senior class, click the Graduate link.
  5. Search for the student, and click the "Graduate" radio button for this student only. Leave all others set to "No Change."
  6. Click Next, and complete the remaining steps, including setting an effective date and time.
  7. After completing all steps, click Save & Exit.
  8. This will graduate the student, giving them the Alumni role.