Oak trees can be killed by removing its bark. It can also be killed by nailing copper nails or by spraying copper sulphate or kosher salt on the tree roots.
Probably the easiest way is to get a hatchet or saw and cut through all the bark in a line completely around the tree. Cutting the bark cuts off the tree's supply of nutrients and it will die shortly after.
not that i like killing trees but if you absolutely need to you can either use salt on the roots or vinegar. You can also try by driving copper nails into it
You can kill an Oak tree by using the copper nails or copper sulfate and also nail some coppernails into it at least i doz. eventually this should kill it.
