What is the ruling on obeying parents who force their 18-year-old daughter to remove her hijab and niqab and work in mixed-gender environments, especially since the workplace will reject the niqab, and the parents are in need of her money?

It is not permissible to obey one's parents in removing the hijab, because it constitutes disobedience to Allah. Covering the face is obligatory for a woman in front of non-mahram men, according to the more correct of the two scholarly opinions. It is not permissible to remain in a job that prevents covering the face unless there is a necessity, while searching for another job where covering the face is possible and moving to it, even if the financial return is less.