To remove users with the Guardian relationship type from your list of parents:
  1. Navigate to Lists > Manage Lists.
  2. Click the Manage basic and advanced lists block under List Actions. 
  3. Locate and edit the advanced list.
  4. In the Filters tab, add a new row under Object Filters.
  5. In the Field drop down, select Parent/Child Relationship.Short Description2.
  6. In the popup, select is not.
  7. Enter the word Guardian.
  8. Click Select.
  9. Follow steps 3 - 7 for each Parent/Child Relationship object in the list.