Salt kills vegetation and plant life. If you have a leyland cypress that has become too unmanageable or is blocking sunlight, salt is a natural and effective way to get rid of it. Using salt water, you will avoid using chemicals in your yard, but be careful about the method you choose for applying the salt. It can kill nearby plants if you're not careful. Although watering the ground around the trunk with salt water will kill the tree, it will also kill any surrounding grass and will stay in the ground for awhile, preventing anything new from growing.
Use a long drill bit to drill a ring of holes near the base of the tree at a 45 degree angle, facing downward.
Mix two parts water with one part salt.
Pour the salt water into the holes.
Plug the holes with mud. After a few weeks, the tree will be dead.