You can cut off small side branches that are not able to help the plant in metabolizing food. i.e. if its not able to get any light and photosynthesize then its not helping the plant. Rule of thumb, if a leave is not dead and is still able to photosynthesize, then leave it alone. But if it is not able to photosynthesize then you can always cut it off. Leaves are like little solar panels that feed the plant energy. If a solar pannel is cover and cannot get any sun, then its not helping in any way, is it. Make sure you dont go to crazy cause you can cause shock and eventually cause hermie. But I have cut half way through flowering and had no issues or hermies.