In nature (outdoors) plants naturually loose leaves due to harsh weather, insects and other acts of god. Removing a few carefully selected leaves from your near perfect enviorment indoor plants will not hurt them. Two weeks into flowering i remove a few big fan leaves here and there only to allow light to penetrate deeper into the canopy but i strictly follow a few rules when doing so.
1. Only remove leaves from the top 1/3 of your plants. I look for the biggest/oldest leaves that are directly shadowing a promising lower bud sites to remove.
2. Remove no more than 1 leaf per square foot of your garden, maximum. For example, if you have a 5x5 room you should not exceed removing 25 leaves total. At that rate you are removing plenty of previously shaded bud sites, i do not believe in any form of extreme defoliation techniques!
3. Always use a sterilized razor to trim leaves, never pull them off by hand which can damage the main plant stems and expose them to infection. You should make your cut leaving roughly a half inch of leaf stem remaining on the main stalk of your plant, this lessen the risk of causing infection or disease to the plant's main stem, the remaining leaf stem will dry up and fall off naturally.