I get that the owner makes the choice. My question regards the choice of eliminating fewer pieces than you possibly could. For example, the Averni can remove three pieces with a battle command. The Averni wants to remove only two of the Belgic allies to prevent the Belgic faction from winning, but not three allies because such a circumstance would lead to a Roman victory. Can the Averni player choose to remove two pieces instead of the three to which he is entitled?
Whay are the Averni choosing how many Belgic allies to remove as a result of a battle? The Belgic player would make that distinction. And as Mark points out, the number of losses stipulated by the involved forces must be removed. You can’t decide to remove less.