Cruelty should never be an option. I'm not a culling chicken owner. I would exhaust all options before it came to that. I know everyone is different. I respect that.
I am of the opinion that he is young and testing out his new found ability. I've always thought of the crow as a roll call to the flock. If something happened recently that spooked them he may call out more frequently to see where everyone is. I'd give it time and try some of the suggestions...