Remove materials assigned to levels

Hi All, is there a programmatic (vba, keyin, anything) way to remove a material assigned to a level?  

Or unload all material palettes?  I can unload them with the 'material unload material_name' keying, but I'm not sure how to iterate through the palettes to get there names.

I just need to get rid of every material in the files.  They are assigned by level.