A wood stump or a kill cone and a hatchet/machete.
Hold them upside down, head facing down, they will calm quickly. Drop it into the kill cone and lob off the head. Quick and humane. If you have trouble catching them, wait until night when they roost to grab them.
Grandma N would throw a little feed at her feet and when one came over she'd grab it by the neck.
Throw it over the stump she used and off with the head using her hatchet.
Chicken/rooster would run around for a bit while she did the others.
Something of an experience the first time I watched her at 4 years old.