I have found this question about bonfire ascetics in a Dark Souls question, and someone has posted an incorrect answer (it is blatantly incorrect) which has been accepted already.
Can the answer be deleted if it is accepted?
Yes. This has happened. This link won't work for non-10kers because, well, it's deleted. But here's the text of the answer:
If you don't see the problem here, clearly you need to disable images in your browser or view source! Who doesn't do that.
![In short, you will get Grilled Porkchop. (This is incorrect, the pig will actually turn into a Zombie Pigman)]
SE is not here to bring answers that look right, we're here to bring answers that are right. Sometimes answerers and askers won't be around to keep their answers and their checkmarks up to date. This is especially a problem if the wrong answer is accepted and highly upvoted.
In those exceptional situations, yes, we reserve the right to take exceptional measures.
No. Accepted answers show what worked for the asker, and can't be changed. Votes show the community's opinion, which is sometimes different from the asker's.
I know it is a little frustrating, especially given how much power the community has to change almost any other aspect of a post, but accept votes are protected.
It should be clear to anyone hitting that page that, although it's accepted, the top answer is not correct.
Yes, accepted answers can be deleted so that the highest-voted answer will be at the top instead. This came up on MSE before.
The thing is that moderators technically aren't supposed to do this to legitimate answers that just happen to be wrong.
Normal users with 20k+ rep can cast delete votes for any reason though.