I assumed the question was how to achieve the proper preconditions for cooking a chicken while avoiding any animal cruelty charges.
Clearly, we could simply knock its head off with a bat, since today I learned you can physically cook chickens with bats and professional batters, via a method well suited to humanity's eminent migration to outer space.
But I expect with some years of strength training and finesse, a very hard flick to the back of the chicken's lower noggin could dislodge the first cervical vertebrate from the skull, severing the spinal cord's integration with the brain stem.
Whether actually dead, or merely in a persistent vegetative state, the chicken may now be cooked.
However, if the chicken is merely headless [0], but in good health, one should not cook it.