A network admin can edit an assistance category and check a box to "archive" that category.
Go to [Admin] tab >> [Demographics] sub-tab >> click EDIT on the demographic field you wish to archive:
When archived, the category disappears from the "Assistance Category" drop-down list in the [Add Assistance] window and in the "Filter by Assistance Category" list in reports.
However, any former use of that category is still in view on assistance records that had been previously entered.