Q.I Have Two Fully Grown Holly Bushes That Have Dropped Leaves And Seem Dead. Should I Cut Them Down And Out?
Both bushes are on the corner of the house. In addition two large Box Hedges have dropped all leaves and died this winter as well.

Certified GKH Gardening Expert
There are many diseases that these two can share. It does seem a lot like one of the many Phytopthora diseases. This oomycete will destroy trees and shrubs, almost, instantly!
This is a tricky one, but this article will offer some insight:
https://www.gardeningknowhow.com/plant-problems/disease/what-is-phytophthora.htm