asexualization

noun

asex·​u·​al·​i·​za·​tion

variants also British asexualisation

(ˈ)ā-ˌseksh-(ə-)wə-lə-ˈzā-shən, -ˌsek-shə-lə- 

: the process of destroying the capacity for reproduction especially by surgical means : sterilization, castration