Put on safety gear before mixing the chemicals. At the very least, protective eyewear and gloves are required. You may also want to wear old clothing.
Cut the bush off 6 to 12 inches above the ground using a hand saw. Make the cut straight across. If the shrub is thick or has multiple stems, a chainsaw will make the job go faster.
Open a bottle of herbicide that contains the active ingredient trichlopyr or glyphosate. Pour the herbicide into a disposable cup and dilute it with water to create a 20 percent solution.
Insert a paint brush into the cup and saturate the bristles with the herbicide. Paint the herbicide on the cut portion of the bush stump thoroughly until it is soaked. Don’t worry about applying it to the surrounding bark, since the cut portion will transport the chemical to the roots of the bush.
Monitor the bush stump daily for signs of new growth, which will look like green buds or shoots near the base. If new growth appears, repeat the entire herbicide application process.