Hello,
I think doing some defoliation is almost always a good move, as long as the plant is healthy and has many leaves. I would go and remove about 4 of those biggest leaves from the top area for some added light penetration, and then as soon as you see budsites forming go in and clean up the whole bottom area of any branches or budsites in the shade of the canopy..that'll channel the energy into the top biggest buds at the most crucial time. You can always do it along the way too if you think you didn't remove enough, or when more grow in as it does it's flowering boost.
Definitely start thinking of a bigger place for them if things are getting tight, however you can open it up for nice airflow and good light.
Happy growing. ✌️