You should be able to inactivate items from the top down without having to go in to delete the BOM from items.
Inactivate a Finished Good, this should allow you to inactivate anything in its BOM [Bag/Box/WIP] so long as its not in other builds.
Instead I have to go in and delete the BOM from the items in order to inactivate them, this is a silly waste of time and removes history for the item.