The main difference between Emasculate and Demasculate is that the Emasculate is a it refers to the removal of the body parts that make a man male, literallly castration and Demasculate is a To take the masculinity from someone.
Deprived of unmanned, weak.
To power; to castrate, to geld. from early 17th c.
To deprive of spirit; to render effeminate; to vitiate by unmanly softness. from early 17th c.
Of a flower: to deprive of the anthers.
To remove the masculinity from (somebody).
deprive (a man) of his male role or identity
“he feels emasculated, because he cannot control his sons’ behaviour”
castrate (a man or male animal).
remove the anthers from (a flower).
make (someone or something) weaker or less effective
“the refusal to allow them to testify effectively emasculated the committee”