Do you mean the bubbles coming out of the filter? That's just a venturi not an oxygen diffuser. All the bubbles do is churn up the water so more is exposed at the surface. As long as the water coming out of the filter moves the water along the tank just under the surface, yes you can turn it off whenever you want.
I would do this, have just 1 cm of the filter above the water line. That would bring the outlet of the filter closer to the surface, then you don't need to use the venturi.