I don't know if a man can have sex without his testicles. I looked up "castration" once (don't ask) and the definition was the removal of the testicles.
To castrate a woman means to take out her ovaries. If a woman does not have her ovaries, it does not mean that she can't have sex.
Castration can mean removal of all the genitals or it can mean to remove the ability to reproduce.