Only little Danny Snyder, the owner, can change the name.
They may have the authority to stop the team from using "Washington" as part of the team name, but I'm sure that's about all they could do.
Personally, if I were the team owner, I'd hold a press conference and publicly and courteously invite the members voting for this to go pound sand. I would also consider moving to a less PC locality, and would take the opportunity to tell them so. Maybe the "Berkeley, CA Indigenous Peoples"!