I have several holley bushes of different varieties that have grown into gigantic proportions (10-12 ft tall, 10 ft wide) and they
need to be trimmed (or removed).

Is it possible to drastically trim these trees?
Or would it kill them?

One of the problems is the leaves are on the outermost part of the bushes. If I trim them more
than a couple of inches all that is left are the
bare branches.

It's late September now and I live in northern N.J.

Thanks.

Well Holly (Ilex) covers several hundred species and hybrids so this is a rather generic answer. While in general Ilex will respond to rather harsh pruning, it sounds to me more like a case of the wrong plant in the spot. I would suggest if you want the mature size to be less than 15% or so of the size that it is now then it seems removal would make sence. It is true that Ilex is a plant that generally can be kept smaller than its natural size fairly easily by regular pruning, once they get WAY out of hand the work involved and varried results generally dont justify the effort. Good luck.