The Grand Ayatollah Seyyed Sadeq Rouhani answered questions about parents disowning their own child.
Question: If the child intends to carry out an act which is not against religion, and the parents are against it, if they tell the child that they will be dissatisfied with the child, and they will disown the child if the act is carried out, is this disowning effective? Can such a method be used against the adult and wise child according to the religion?
The Grand Ayatollah Rouhani: If an act which is not against religion but the parents say must not be done, and the parents will be dissatisfied if the child carries it out; then the child must not do it, and if the child does it, it is against religion. In brief, in non-Wajib cases and forbidden acts (Moharramat), it is Haram to oppose the father and the mother, in such a way that they are bothered by that act.
source : shafaqna.com