My answer to Can I move 240' and attack in one round by using two riding horses? is factually incorrect, but was accepted before I realized that. I cannot delete the accepted answer. Is there any way to remove the post?
Flag as “other” and explain the issue in the custom flag area. Moderators have the ability to delete answers even when they've been accepted, and unless there's a good reason not to, such flags are generally acted on.
Before I got my diamond I ran into this at least once and used a custom flag to request my accepted answer be deleted, and that took care of it.