The first question we have to ask when starting a data load is what type of data load you are doing. Here are some of the types of data loads:
In order to remove a set of parts there are a few ways to approach the problem.
If you are trying to permanently remove items please note that System Five will Remove where possible, and mark for deletion the rest. I don't believe the toolbox routine looks at Marked for Deletion items.
If you are looking to import invoices, the big question is WHY?.