I asked a yes/no question, got no satisfactory answer, so just want to drop it. From what I know (I am still a newby), the only way to do this is to answer myself, and accept it. Is this the right way to let a question go?
In that instance I would say you should answer it yourself and mark that as the correct answer.
You will sacrifice 2 rep points (that you'd get for accepting anyone else's answer) that way - but that's better than suggesting a poor answer is a good one.
If you don't want it to show anymore you can vote to Delete it, of Flag it for moderator attention asking to delete it.
You can also just leave it be then it's up to the community: if it won't get any upvotes it will get automatically deleted, as far as I remember after one week from the last edit.
If there are answers and you still want the question removed from SO your only option is to Flag it explaining why you want it removed.
If you're concerned about your accept rate and do have correct answer already then by all means post it yourself and Accept it.
Edit: I see you already did this. :)