No, but there should be. You can get your question or answered deleted by e-mailing the AB Editor but that's pretty much the only way at the moment. Good suggestion.
The problem with deleting existing answers is that it would sometimes make a nonsense of subsequent answers. You'd get someone writing: "I disagree with..." only later to find that no such opinion had ever been - seemingly - expressed! Of far greater usefulness would be an edit function, so that slip-ups in answers could be amended at the time.