Q:

Protocol for deleting wrong answers. 

Assume someone asks a question, I read it and think "ok I've got it".  And post my answer.  After some amount of time I realize, or am alerted that my answer is wrong.  Perhaps it was too sloppy, or missed a special case, or even maybe I misunderstood the question.  Also assume that in the mean time, someone else has answered the question correctly.  Their answer has been accepted and all is well. 
Should I delete my answer? 
I don't think this matter is super important, I was just curious. 

A:

If it's entirely wrong and of no value to future visitors, why not delete it?  It's less clutter that way. 
If your answer does have something of value not covered by other answers, please don't delete it just because something else is better, although you can edit it to remove the incorrect or irrelevant parts.