You'll get varying opinions on defoliation- some strip them down almost bare, others only remove the the big fan leaves up top, and others swear to never remove a leaf. It really boils down to your situation. Genetics, limitations of your grow lights and humidity factors all play a role in those decisions. My advice is to experiment with it if you're interested in the outcome. Thin one side more aggressively than the other and see how your plants respond then decide.