I typically don't like to kill trees. But this is an awkward situation.

There is an oak tree growing in the middle of the hedges that are in the front of my house. In my stupidity, I cut the tree near the base last year. Now it has created many small branches. It is now affecting the hedges around the house. The tree is too big to pull out but yet its difficult to kill.

How do I do it? I am guessing its about 2 years old now.