We have a Category Set with an Dependent Category Set that we want to delete from thousands of items

We have a Category Set with a Dependent Category Set that we want to delete from thousands of items. How can I use the Category Interface to do this?

Example: Category Set   Brand, has a dependant category set called SubBrand.   We want to unassign thousands of items from both.  We can't figure out how to populate mtl_item_categories_interface to do this.  Because of the dependancies, we continually get errors. 

If the Category Interface can't do this, does anyone have other suggestions?