Leonin Bola grants an ability to the equipped creature. The ability can target a creature with protection from artifacts (unless the equipped creature is an artifact creature).

“Unattach Leonin Bola” means just that — Leonin Bola moves off the creature it was equipping and remains on the battlefield.

The equipped creature’s controller chooses whether or not to activate the activated ability. It doesn’t matter who controls Leonin Bola.