The way of deleting supply only sub categories to be changed

Within Access Maintain system if you go to any sub category that is under Supply category->Product catalogue and click on "Edit" there is a delete button that would remove the whole sub category and ont only the sub category assigned to one specific contractor. The ability of deleting only that specific sub category assigned to the contractor rather than the whole sub category from the system would be beneficial otherwise it will require to be reinstate by our development team.