Kakashi Hatake attempting to kamui Deidara in order to send him to another dimension.
Battlefield removal (or BFR) refers to the act of one character forcing their opponent out of the established fighting area, resulting in a default win.
If the battle arena has established physical boundaries that the fighters aren't allowed to cross, then a BFR can be achieved by forcing the other person to cross those boundaries. Some examples of this would be:
- The Hulk punching his opponent out of bounds
- Shikamaru using shadow possession to make his opponent cross the boundary
- The Flash bringing Gorilla Grodd into the Speed Force with just his mind.
If the battlefield doesn't have established physical boundaries, achieving a BFR is tougher and less likely, but not impossible. Generally, it's done by trapping the other person in another time or dimension. Some examples of this are:
- Kakashi using kamui
- Obito Uchiha using space-time migration
- The Doctor trapping someone in a time loop