Mike the 1st level Monk is in Monastic Archer Stance, so he can only make Strikes with a bow. It is his only stance.
A Skeletal Champion comes to an adjacent position, and Mike knows that they have resistance to piercing damage, and have Attack of Opportunity, so it would be a really good idea to just punch it in the face, instead of trying to shoot at it. However, it seems he just cannot stop it.
Stance (Core Rulebook p637):
A stance is a general combat strategy that you enter by using an action with the stance trait, and that you remain in for some time. A stance lasts until you get knocked out, until its requirements (if any) are violated, until the encounter ends, or until you enter a new stance, whichever comes first. After you use an action with the stance trait, you can’t use another one for 1 round. You can enter or be in a stance only in encounter mode.
He does not want to be knocked out. The encounter will end with his death if he cannot use another attack mode, and he does not have another stance. Dropping the bow would violate the requirement (wielding a bow), but it might not be a good idea in the middle of the fight, especially if the Skeletal Champion has archer buddies.
Can Mike change from wielding to holding the bow? Is there another way to stop a stance?