How can I purge unused padstacks in board database?

OrCAD Capture 16.6, OrCAD PCB Editor 16.6: 

I cannot seem to be able to remove unused padstacks from a board database.

I edited an existing complex board (6 layers, hundreds of parts, vias, text elements, etc) as follows:

1. Opened the board and enabled global visibility.

2. Unplaced all symbols (unfixing when necessary).

3. Removed all etch, shapes, lines, text, vias, groups, dimensions, figures etc (i.e. everything visible, unfixing when necessary).

4. Opened the constraint manager, went to the physical contstraints and removed all vias in the via list except one   (note there are no BB vias).r

5. Imported logic from a schematic that had just one component from the original design with an unnamed signal net connected to each pin.  The part has just 3 pins with two unique padstacks, one of which is a flash shape.

6. Placed the one part and completed the rats.

7. Checked DRC OK, checked the database OK.

When I export libraries to a directory, I should have just one symbol, three padstacks and a flash symbol.  Unfortunately, the library directory contains over 200 files, most of them padstacks.  I tried back-annotating, re-generating the netlist and importing again, closing and reopening, etc to no avail.

It seems as if the board database never forgets the old unused padstacks.  How can I "purge" the database so that I get only the parts and padstacks that are actually there?