You can target the leaves deep inside or under heavy canopy but wait until they yellow off first. In the final weeks just before chop you can pull off any dead or shriveled fans. Otherwise never pull off healthy green leaves during flowering without good reason.
Early defoliation during bloom phase can result in smaller buds. The exception is plants still in veg; you can always just let them grow back if you cut off too much while the plants are still in growth phase. Sometimes if you are training out a lanky plant it's better to top and prune to promote lush new growth and tight nodal spacing.