Unusual occurence in April 28th Baltimore-Cleveland game

[SAump]

Where in the rulebook does it state that an umpire can wipe off an earned run by mistake?

The defense saw the umpires were still wondering about the play in question too. Both sides put in their arguments and the umpires corrected the mistake, albeit 3 innings too late. I believe there is a precedent to changing the official score to reflect player statitistics such as RBI awards. The defense should have been well aware of the mistake the umpires had made. I guess instant replay was shown and everyone knew the umpires had made a mistake. The right thing to do would be to withdraw the protest, if possible, or throw it out, if not.