You can remove the Student Role, but first, ensure that they do not have any enrollment rows.

To remove the Student Role from the User, navigate to:
  1. Core > Users > Edit User Profile Data > Search for the User
  2. Click on the Name of the User
  3. Scroll down to System Information Click Student Enrollment 
  4. Click Enroll in School
  5. Select the Current School Year Select any Grade 
  6. Un-mark the include in Future Enrollments checkbox
  7. Click Save & Exit
  8. Click Edit into the New Enrollment Row
  9. Click Delete
  10. Click Confirm