If Castration Stops MPB, How is Female Hair Loss Possible?

I’ve read many times that castration will stop male pattern baldness, in that case how are there forms of female hairloss?

Male pattern baldness occurs in MEN (as the term implies). Female hair loss has nothing to do with men or for that matter androgens (males type hormones made by women, including low doses of testosterone). It is considered genetic, but it is not cause by the male hormones women produce.