Which is exactly why you should follow
@Indacouch advice as well as the others who've echoed what he's stated.. The plant is still using those leaves and when you remove them, it just moves up to the next one.
Yellow leaves do not attract fungus gnats/pests. The "color" yellow does but you either have them or you don't. They don't just magically show up. I also wouldn't recommend lolipopping until the 2nd or 3rd wk when the stretch is over or else you risk stunting your plants.
Pay attention to who you take advice from. Go check out their grows and you'll see who knows from experience who's regurgitating what they've "read" on the net.
Google =/= experience.