Rule 506.4

A permanent is removed from combat if it leaves the battlefield, if its controller or protector changes, if it phases out, if an effect specifically removes it from combat, if it’s a planeswalker that’s being attacked and stops being a planeswalker, if it’s a battle that’s being attacked and stops being a battle, or if it’s an attacking or blocking creature that regenerates (see rule 701.19), stops being a creature, or becomes a battle. A creature that’s removed from combat stops being an attacking, blocking, blocked, and/or unblocked creature. A planeswalker or battle that’s removed from combat stops being attacked.