Hi Still!
You´re not clear about you want.
If you need delete, you need identify what materials not apply in your cube, but you need to analyze. To do that, you need check with your user, what material not need, and may be you need use 0BILL_TYPE or may be 0Material with 0MATL_TYPE attribute.
Anyway, you need validate with user before any change.
Regards.
Frank.