Palms only grow from a terminal growing point. If you cut it off, the plant dies period. You could get away with removing a few of the lower fronds if they are in the way (but you have to be careful and not overdo it as this too can set it into a decline). If you want something shorter, consult some local experts to suggest some shorter growing.

Change them now, to some other plant. Areca palms in South Florida will grow to over 30' and yours will only get bigger. If you don't want something that tall, replace them with a hedge if you want privacy or a smaller palm if they are a focal point.

Thanks for the posts. Looks like I have some work to do. It's a real shame b/c they are doing so well.