The Collaborative International Dictionary of English v.0.48:
demasculinize \demasculinize\ v. t. to remove the testicles of a male animal. Syn: emasculate, castrate. [WordNet 1.5]WordNet (r) 3.0 (2006):
demasculinize v 1: remove the testicles of a male animal [syn: emasculate, castrate, demasculinize, demasculinise]