Can my ex-husband terminate his parental rights to avoid paying child support?

Short version: "no." Consider this case holding: In the Matter of Parental Rights as to T.M.C., 118 Nev. 563, 52 P.3d 934 (2002) The Court concluded termination would only serve the father's personal financial interest, and held a parent could not voluntarily terminate his parental rights and obligations unless such termination is deemed to be in the child's best interest, and even if the parent engages in conduct that satisfies NRS 128.105, the child's best interests must be served by termination of parental rights for such termination to be appropriate.