Does the man who became the guardian of the new Muslim girl remain her guardian even after her marriage? And does he remain responsible for her in cases such as divorce? If so, how can this guardianship be transferred from him to another person?

If a woman embraces Islam and has no Muslim guardian, the Muslim judge marries her off. If there is no judge, the Imam of the mosque or a just Muslim man marries her off. This marriage does not make the one who marries her off her guardian, and she is not obliged to refer to him in any matter after the marriage contract.