This question has the actually correct answer directly beneath the wrongly as correct marked answer:
How to turn off spelling and grammar check in OneNote on Windows 10
Can this somehow be changed?
This question has the actually correct answer directly beneath the wrongly as correct marked answer:
How to turn off spelling and grammar check in OneNote on Windows 10
Can this somehow be changed?
Contrary to common sense, an answer being accepted doesn't always mean it's correct. It just means that the answer was considered the most helpful/best for the OP at that time.
Considering that there's a comment to revisit the accepted answer on July 26, and also considering that the OP is still active (last seen 15 hours ago at current writing), removing the acceptance mark by force can be considered as an abuse since it's OP's privilege to choose any answer that considered as the most helpful.
While there's an occurrence of unacceptance by a mod on another site, it's not a usual case that the mod will lightly follow. So, don't flag the answer being wrongly-accepted because it's not mods' task to decide the technical correctness of an answer.
Instead, you can try to comment on the question again to ask OP to consider updating the acceptance. However, (and as said before,) OP is free to choose any answer they deem the best.