When your boss says you can have a raise but the president of the company steps in and says that you cannot have a raise so the raise never goes through, this is an example of when the president overrules your boss.
In Brown v. Board of Education, the Supreme Court overruled Plessy v. Ferguson.
The defense attorney's objection was overruled by the judge.
Overrule a decision about hiring a job candidate; overrule a call by an umpire.
Overrule an umpire.
The line judge signalled the ball was in, but this was overruled by the umpire.