hmm time for a diagram...
I assume you are talking about 3 or 15, yeah you can leave them out but I would get smaller OD washers of the same thickness to fill in the gap, otherwise you won't might run out of threads and not have the correct pressure on the bushings at the top of the shock. You probably want to cut the bumpstop one or two sections shorter as well to complete your ghetto-drop, although be aware you stock shocks won't las long with any sizable drop.