Here's why:
* Mirror Force is a Trap Card that only activates when your opponent declares an attack with a monster.
* Mirror Force destroys all face-up Attack Position monsters your opponent controls.
* Banishing is a separate effect and not a part of Mirror Force's functionality.
To banish monsters from your field and graveyard, you would need to use different cards that specifically have those effects.
For example, "Call of the Haunted" allows you to Special Summon a monster from your graveyard to your field. Then, you could use a card like "Solemn Judgment" to banish the monster from the field, or "Black Horn of Heaven" to banish it from your graveyard.
Remember, each card has specific effects and limitations. It's important to read them carefully to understand how they work.