I found this website when I was looking into options for a friend's rooster; he was crowing way too loudly and she wanted to keep him but was running out of places to hide him inside her house so the neighbors wouldn't hear. This site gives a decent crash course on how it's done. When I got to reading about how certain practiced farmers could do it with a V shaped nick in a finger nail, I figured it was well beyond our capabilities:
https://www.countryfarm-lifestyles.com/caponize-chickens.html
It does mention a high mortality rate, especially for those first learning how to do it. And the methods described in there seem pretty horrific...I baby my chickens and so did my friend so it very quickly became "not an option" for us. But I'm definitely not here to judge or make assumptions about anyone who chooses to do it.