Warning: this subject can be upsetting to some people.
It’s hard to take a life, even if it’s necessary. There are many reasons why you would need to know how to kill a chicken. Sometimes if they’re injured and need to be put down. Sometimes they just get old and it’s time to cull. Or if you’re raising chickens for meat, you’ll need to know this valuable skill.
Most importantly, you don’t want to say to yourself that you’ll never do this to YOUR chickens and then be put into a situation where you MUST.