how can i kill black hornets?

Answer 1

Before I tell you how to kill them I first want to assert that hornets are gentle giants and really have no interest in you. They will not sting without provocation and if they are busy in your yard pollinating then they will totally ignore you. Anyhow, if your problem is dire and you are phobic then you can get a wasp and hornet spray that will shoot up to 20 feet so you can remain at a safe distance. I think raid makes a good spray.
Good luck

Answer 2

For safety's sake, best to call a specialist.