Whats the best way to kill an oleander bush?

[Hermann Cheruscan]

I've got an oleander bush that I'd like to get rid off. I stopped watering it a couple years ago, and still it lives. I trimmed the branches down to nothing last year, but they grew back. I've even poured small amounts of gasoline around the base, just to try to kill it, but nothing works.

Does anyone know if I could get something at a garden center to poison this thing. I know I could just dig it up and hack at the roots, but that would take all day.