From the Boston Globe (competition newspaper): Local historians say Peter Faneuil, a wealthy colonial merchant who gifted the hall to the city in the 1740s, owned several slaves and participated in the slave trade.
Thanks for the readable link.
This seems likely since, at the time, Massachusetts was a slave state. In fact, of the original 13 states, 13 of them were slave states.
There is no logical reason to rename the building. If the building's history is tainted beyond redemption, the best thing to do is to tear it down. And rename the slave state of Massachusetts something else.
I, too, condemn slavery in the strongest possible terms.