Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The Awrah (parts of the body that must be covered) of a Muslim woman in front of a Muslim woman is from navel to knee. Therefore, if you are assured that alien men or non-Muslim women cannot see you then there is no harm to remove your headscarf; otherwise, it is forbidden. For more details, please read the Fatwa: 81343.
Allah knows best.