if you cant wear apostal mail bag but you have been dilivering mail like that due to a physical disability for about 15 years does the post office have the right to say you are not fit for duty and prevent you from working

if you cant wear apostal mail bag but you have been dilivering mail like that due to a physical disability for about 15 years does the post office have the right to say you are not fit for duty and prevent you from working