Assalaamu alaikum, There is a fatwa on here about the permissibility to shave the beard while training for an occupation (airline pilot) that was assumed to benefit the individual and the muslims. There was no suggestion he try another occupation that can help himself and the ummah and did not require removing the beard during training.
My question is then would it be permissible for me to remove my hijab during working hours for similar reasons of necessity? It would only be during working hours. I would have no other means of adequate financial support except working. That job could benefit myself and other muslims as well.

All praise be to Allah, and may His peace and blessings be on the greatest messenger, Muhammad.
There is a great difference between the beard and hijab. If a man asked whether he can work for a company that would not allow him to make his prayers, the answer would have been no. You must consider the degree of need and also the injunction to be compromised in tackling such issues.
The Muslim woman is not allowed to take off her hijab except in the case of necessity (such as if she had a legitimate reason to think she would be attacked if seen with the hijab). These extreme conditions happened and may happen, such as during the Spanish inquisitions or during the massacre of the Muslims in Bosnia…etc.
It is noteworthy here to say that the Muslims are required to immigrate if they cannot practice their religion.
In the USA, currently, there are many Muslim women who work with their hijab. It is preferable that the Muslim men try to suffice their families, so if the woman had to work, she may work from home or within the Muslim community or do a job that will respect who she is and her religious practices.
As for those sisters who do not have a provider, they should find one of those jobs where her religious practices are tolerated.
If there is a particular case of necessity, it must be addressed individually.
Allah knows best.