I'm pretty sure this happens to someone out there now and then:
You've read a question, done the work with writing a pretty decent answer, at least you think you have, then you find some detail in the question, either edited in at a later time or maybe not clearly defined in the title or pointed out in the context in the first place, that makes your answer either get down-voted because it isn't the most accurate or relevant answer or just kinda misplaced because it answers what you thought was asked, but then again, meh...
So, it isn't directly wrong, but neither a good answer for the question when you realize that you misread the whole thing. Could be that something got lost in internal translation (like inside your head, for non-native English speaking folks) or just poorly written. Could be you rushed for a bounty, at 4 a.m after a couple of beers, whatever.
What is the best approach in such cases? Should I (or could I) delete my answer? What are the rules for if / when I can delete an answer? Come to think of it, I really don't know the rules for if / when I can delete my own questions either... Is this written somewhere?
Does deleting an answer impact anything other than what it sounds like, e.g. the answer is Poof! gone or does it cause any other reactions / rep changes? Is it considered bad practice to do so, if at all possible?