What is the ruling concerning the money I received from a university scholarship after discontinuing my studies, while remaining registered and having obtained permission from the granting body to withdraw it? And is it obligatory for me to withdraw my registration or donate the money if it is unlawful?

If the granting authority permits the disposal of the grant, then there is no harm in doing so, and it is not obligatory to donate it as charity. However, if it becomes apparent that you are not entitled to the grant, then it must be returned to the university if possible. Otherwise, it should be spent on general public utilities for Muslims or given to a poor person, and a poor father has a greater right to it.