No, growth regulators won't kill it.Regularly cutting it down may slow it down. But never allow it to get this tall again.

If this is a common nasty weed in your area, several local agencies may have advice, among them Soil & Water; Conservation & Soil District; and your county's Extension Service office.

You an locate the latter using this map: http://nifa.usda.gov/partners-and-extension-map

Where in the world are you? Some sources indicate this is a grass that grows in warm climates and is a plant that prefers wet soils.

kimmq is kimmsr

i am in the Caribbean