Yepper, I always pull the dead, and 50% dead leaves. If the leaf is yellow, the Chlorophyll, ( thats the pigmented molocule that absorbs light and converts C02 and H20 into usable carbs) is not present, and therefore, the leaf is past its useful stage. In addition to this, long before the leaf yellows and dies, the stomata, ( these are the aperture like openings on the leaf underside through which the leaf transpires), ceases to function. So.... yeah, be judicious, but you can pull those mofos