Yes he can, provided he flies in accordance with the VMC minima relevant to the class of airspace. It would be a brave man who would file a flight plan which might restrict him to certain routes or levels and be sure he could remain 1000 ft vertically or 1500m horizontally from cloud and/or clear of cloud in sight of the surface etc for the whole flight. Remember you are also subject to the more stringent minimum height rules under IFR. To my mind, once IFR is cancelled it would be difficult to keep refiling it once you are back on track clear of your particular cloud.
Don't confuse Instrument Flight Rules with Instrument Meterological Conditions, or Visual Flight Rules with Visual Meterological Conditions. On an IFR flight can you can fly a visual (conditions, not rules) approach to an airfield, but you are still subject to the separation and restrictions afforded to an IFR flight. You are in VMC but under IFR (as are most airliners at altitude).