There would be no point, and you couldn't do it. If it's already dead and somehow still moving.... like, I don't know, a corpse that has gears in it, just destroy it. You can't "Kill" it, since there's nothing to kill, so you'd just dismantle it/blow it apart.
A dead thing that still retains its powers of locomotion can't be killed - but can be broken. Think about it like this - a car is dead yet still moves. A robot is dead, yet still moves. If we want to stop the car or the robot from moving, we break it/smash it/destroy it. We don't "kill" a car or "kill" a robot, after all.
So to answer your question: You can't kill what's dead. Killing implies the taking of life, and if there's no life to take, then you can't kill it. You can smash it, break it, cause it to decay or immobilize it, but you can't KILL it.