Um... I don't see the harm in trying it. Are you sure the cola is ready to harvest? Did you microscope it or are you eye-balling it?
Anyways... I don't think cutting the top off your plant will kill it or harm your lower buds so if you think you'll benefit from cutting your cola now and leaving your lowers, do it.

(Once a plant is well into the flowering process it's impossible to re-veg, regardless of your lighting schedule)

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MaryJane & Talking Bunnies. (Click).

Nothing of what I say is factual, nor do I.. do.. fuc, im so fucking baked right now....