Can a father forego his rights on the child

My husband deserted my eleven month old son and me in Dec 2012 since my father was unable to meet his family's financial demands. He wanted to remarry n filed for divorce on cruelty grounds.. I contested. In Jan 2016, his parents asked us to withdraw the petition n said they will withdraw theirs n will resolve the problem amicably. We withdrew. But they had continued the case and took divorce as ex parte in Aug 2016. The news came to me as a shock in Jan 2017. Set aside petition was filed and is going on.. We are going for mutual consent Tomo. He had not come to see the child even once after he left. We took the child to meet him during the early days of the problem but they declined to even meet us.. I am the sole care taker of the child. I do not want any alimony from him. Can I ask him to relinquish his rights over the child as a father n that he will not disturb the child in future..?? Becos I heard his parents say that they will claim the boy after he grows up. Pls help.