There has to be someone around that would eat the meat. Why kill if you won't eat them, or your family won't? Advertise them on Craigslist, either as laying hens or meat
I did this, to an extent. Got rid of all five of my older girls, gave them away on Craigslist to a lady who wanted older hens for her rooster. Then cleaned out the coop and got 7 chicks. They will be fine all winter in my coop but as soon as they feather out and get big enough, I'll open the...