 Cutting the lower limbs away from the lower part of a tree is not going to do any good for the tree. It's maybe not going to hurt it so bad it's going to injure it and cause insects and diseases to come in or even kill it. But don't think that that's doing any good. When you're cutting on a tree, it's doing some damage. So you do as little as you need to do is the answer to the question on the pruning.