Fan or Sun leafs serve a very important purpose to the over all health of the plant and the final size of the flowers too at harvest time.

You should understand that the plant needs those leafs to regulate the internal temperature of the nutrient uptake. MJ will grow best with in narrow, given temperature range so if the grow area suffers from high temperatures for a period of time then you will get larger fan leaves to compensate. With cooler temperatures the fan leaves do not need to be as large and if you can keep the temperature swing within 5° (+/-) of 75°f over 24 hours and through the entire grow cycle you will have leaves that are all about the same size.
Fan leaves do serve a good purpose so leave them alone. Tuck them under but do not cut them, you could raise the internal temperature of the plant and send it into shock or stunt its growth.