What should I do with my 18-year-old daughter who wants to remove her hijab and is not convinced by it, after all my attempts to persuade her have failed?

Parents are responsible for raising their children, enjoining them to good and forbidding them from evil. They must clarify that the hijab is a command from Allah Almighty, not merely a social custom, and that a Muslim is commanded to submit to Allah's rulings, and that a Muslim's faith necessitates obedience to Allah and His Messenger. If the daughter has doubts about the hijab, these must be dispelled with the help of scholars, while exercising wisdom and encouraging her to associate with righteous women, strengthening her faith in Allah and the Last Day, and making abundant supplication.