I know there isn't button to do that, but is possible in the future the forum have that feature?
Because I've mistakenly reported my post to a moderator by accident.
If you're worried that it will be an accurate report, just make another report with the reasons for withdrawing the previous report. I don't know if the results will be effective, at least this is what only you can do.
So far, I reported 3 posts with 100% accuracy, 1 of the 3 reported is my post. I don't know how that 100% comes, because my post i did report some time ago, maybe still be unhandled or hasn't been seen by a moderator. (It might also a bug percent calculation)
Even if you report your own post and it is marked as good, it will count towards accuracy.