Is it permissible for a woman who wears the niqab to remove it to work in America, knowing that she lives with her husband and children on his income, and there would be no other income if something were to happen to him?

A woman is not permitted to uncover her face if she knows that men will look at her. If it is possible to perform the work while covering the face, there is no objection to it. However, if the work necessitates lifting the niqab, it is not permissible except in cases of necessity.