It is the apocalypse after all.

Here's the tedious way, which requires only a hex editor and reckless abandon of optimization:

Well this work, I thought the "remove item X from inventory" was subtracting 1 from the current item quantity, that's why I didn't thought the event route was the most practical one. Even then, you could with notepad++ and uses or copy/paste/replace write fairly fast the event of 99 times a removal of 1 * 255 items. It's just that it would take about 5000 bytes of free space lol