I thought I had an answer to this question. My answer was accepted and got 2 up votes, but then I realized that it doesn't actually work. I updated the answer with a semi-retraction, but I don't know what else I should do.
Is there a way to remove its accepted status?
Is there a way to promote the question again, so it can be answered correctly? (I'd really like to know the answer!)
In general, no, only the asker can unaccept an answer. In this case since the answer no longer answers the question, I converted it to a comment, so the question is considered to have no answer now and will show up on the unanswered list. You can further promote a question by putting a bounty on it, although you don't have enough reputation to do that yet
In case you wondered (like I did), but did not try: you cannot delete your answer once it is accepted, but it can be deleted through moderator intervention or by being flagged, as described here. (Some selections after flagging bring out moderator attention as well).
Your question here on meta is valid and had the result you wanted, but I don't think we want to have a question here for each accepted answer which has similar problems. So the right thing to do in these cases is flag your own answer for moderator attention, and select 'other' with an explanation. You can of course include a proposed course of action for the moderator there as well (complete remove, only unaccept, convert to comment, etc.).
