This question already has an answer here:
Are there any canon sources of a person using the Force to deactivate an opponent's lightsaber during combat?
There's a question of whether a lightsaber even needs an activation button because somebody could just use the Force to activate it. There's even a comment there about somebody using the Force to deactivate a weapon,
If a lightsaber was only activated by the Force, how would that stop a Sith from deactivating a Jedi's lightsaber?
but as far as I can tell there's no question of deactivating one during combat as suggested by the comment above.
There's also a question of using the Force to power a lightsaber. (Different from activating one using the Force.)
But no question that I found about merely deactivating one to disarm an opponent. Seems like a fairly simple way to win a lightsaber duel. Has anyone done this during combat?