You can cancel your automatic top-up through Easy top-up page. You can continue using your YU plan with manual top-up. Keep in mind that the manual top-up doesn't come with double data. You'll get 2.5GB instead of 5GB or 10GB instead of 20GB based on your top-up amount.
If you wish to opt-out from the YU plan, send SMS 'STOPYU2019'. Any remaining benefits will be removed upon cancelling your YU plan.