I live in Monroe (Zone 7). Two years ago I planted 3 Arbutus ‘Compacta’. I have never pruned them. This year they took the cold winter pretty hard: over half of the leaves are golden/brown/black, with some already falling off. Will the leaves be replaced or do I need to cut the branches and stems to those leaves and hope for the best? The tree/shrubs are in well-drained soil, mulched, facing south/southwest. The leaves hurt the worst were on the upper and north facing side.
It sounds like you are seeing winter damage on your plant. You should probably wait and see if the plant returns to more robust health, and to see if new growth develops where those leaves have dropped before deciding whether to prune it at all. The local web site Great Plant Picks indicates that Arbutus unedo ‘Compacta’ can be cold-sensitive. Arbutus unedo ‘Compacta’ tolerates a wide variety of soil conditions. It grows best in part or full sun and is drought tolerant once established. There are few insect and disease problems, though it can occasionally get aphids and there may be fungal spotting on older leaves if grown in very poor soil. Foliage and flowers may be damaged in extremely cold winters. If you think that there is something else going on besides winter injury, I would recommend taking a sample to a Master Gardener Clinic for diagnosis.
Below is information on winter injury from Washington State Extension and the Pacific Northwest Plant Disease Management Handbook.