Can you undo a vote?

[Carolina E.]

I was on my phone looking at the site and accidentally voted for a post.   It is not that big of a deal, but was just wondering if there is a way to undo the vote?

[Andrew Syrios]

Just quote the person, tell them they're comment was actually a horrible waste of time and you sincerely regret ever having laid your eyes upon it let alone voting for it. Inform them that that if you come across another post they wrote that is actually vote worthy (an extraordinary unlikely event given the quality they have so far demonstrated) you will abstain from voting as an act of principle. That should do the trick.