Is a sister permitted to abandon the hijab on the grounds of having been coerced into it at a young age, and is the repentance of the mother who encouraged her to do so considered sincere and valid, given her statement that she might revert to her previous actions?

The Muslim woman must wear the legal hijab (definition) in obedience to Allah and His Messenger. The guardian must compel his daughters to wear the hijab. It is not permissible to obey parents if they order the removal of the hijab. The statement "I want to wear it out of conviction" is one of Satan's whispers. The duty is to clarify the sister's error, admonish her, and warn her of Allah's punishment, all with gentleness and prayers for her guidance.