I'm a total bottom who has always wanted to have my penis and balls and sac removed. I don't need them or want them really. I worship cock and sperm, but other guys cocks and sperm, not mine, (though I do eat my own cum, I don't enjoy it nearly as much).
While the fantasy cutter scene is fine as fantasy, if you want to live through it to enjoy being a nullo, you should avoid that scene and get a doctor to do it. There are a number who offer penectomies, and variations of castration, including removal of the scrotum, which I'd want. Then you need to consider what kind of hormone replacement you want.
Sadly, my insurance doesn't cover enough, but when I can afford it, I will do it.