Plain rubbing alcohol is a cheap and easy way to kill anything from a weed to a tree. Just rub it or spray it on the leaves evey few days. This also avoids poisoning the ground like what happens if you use salt to kill plants.
Salt will usually do it. I am sure bleach would too, but salt is less toxic to people and pets.
It can kill what you see, but their roots are very strong, therefore the only real way to eliminate it is to pull all the roots out!
I have a yard with English Ivy. It is invaded by poison Ivy. What can be sprayed on to kill just the poison Ivy?