Q.How to take care of schefflera plants
One of my schefflera plants has lost more than half of the leaves. The leaves don’t look healthy. Another one has lost all the leaves, but the stem is still green. Would you suggest pruning to get new leaves or should they be kept indoors? They are kept in the deck away from direct sunlight. They are watered as suggested. The temperatures range from 75 to 100 degrees.

Below is an article on the care of schefflera plants that will help you - verify that you have been watering it correctly. I think that repotting your schefflera in a pot the next size up in fresh soil would be a good remedy. You may also prune them as you suggested - schefflera respond very well to pruning.
https://www.gardeningknowhow.com/houseplants/schefflera/schefflera-plant-care.htm
Happy gardening!