I was browsing the top sequences-and-series questions for fun and stumbled upon this problem, where the only answer is incorrect (the user misconstrued the problem and tiled $[0,1]^2$ with rectangles of the right area but wrong sides). In the past I have flagged such answers as 'not an answer' under the interpretation that answers must be correct, but the flags are often disputed. So I flagged this answer as 'in need of moderator intervention' and explained the reason the post was incorrect and should be deleted. The response was 'declined- flags should not be used to indicate technical inaccuracies, or an altogether wrong answer'.
So, if we can't flag incorrect posts as Not An Answer or use them to bring to moderator attention, what recourse do we have to remove false answers, especially from old questions? On older posts sometimes there isn't an option to flag as 'very low quality,' which compounds the issue.