are we talking about this edit that looks like vandalism to me i have no idea who mr pena is but the ip modified someone else's comments and added something that looks like irrelevant nonsense to answer your question i doubt there's a written rule anywhere about removing obviously incorrect warnings but it falls into the category of things that are obviously a good idea if someone is a good faith user we don't want to drive them away by falsely accusing them of vandalism but in this case i would not suggest removing the warning you should only remove the warning or replace it with a personal message if the edit was obviously not vandalism