And when larger ethnic groups are considered, there are the Fighting Irish and the Minnesota Vikings (for starters).
This does not ban the Redskins from calling themselves Redskins, but it makes it harder for them to sue to stop knock-offs. I’d say they should stay Redskins and find as many American Indians as possible who like it (and there are a lot). And endure the knock-offs which at this point would only make them more famous, not less.