I agree with cutting the head off as the quickest. Shears is the easiest for me. I hold the body so the wings won't flap and just a quick snip and that is over. Continue to hold the wings against the body or there will be a reflexive frantic flapping. That is only a reflex but is troubling to me so I just hold them until that passes. Some people can just snap the heads off by hand, but I can't do that either. I have shears and a hatchet, but for that age/size I'd just use the shears. Culling is a difficult part of it for sure.