Your trees look healthy to me. That gray green lichen growing on the trunks is just lichen. Its not a disease or harmful.
To what you want to remove are water sprouts. Branches growing straight up
What you want to keep are Fruting Spurs
For branches not growing straight up reduce the terminal buds at about the third forth bud so it turns into a spur.
To keep your trees from droping fruit you have to thin the fruits.
1-3 fruit per spur
