Sent my George to Camp Kenmore for the very same reason. He was sweet as pie for a long time, then started stalking people. I ignored it. one night my 13yo daughter went to the coop to medicate a different bird. He flew at her head, scratching her face & knocking her glasses off, breaking them. That was it. He went to Camp Kenmore that very night.
There you go. After a beloved pet rooster injures somebody you grow less fond of him and swinging the axe becomes easy.