The fundamental objective in a game of football is to score more goals than the opposition.
That is not the same as outscoring the opposition by the maximum possible number of goals.
In a league game you would be entitled to do so because there may be a point where goal difference is an issue, but in a cup game there is no justification.
If you are, say, one or two ahead, going for more would be a good idea; because the other team might start scoring and get back into it
However, if you are into the last ten minutes and you are, say, four ahead, that game is over, the winner has been established. Acknowledge that, play the game out and move on.
No one is there to be humiliated to to humiliate anyone else.