big plant in small box

Probably not the answer you were hoping for but I'd say that one of those has to come out and have a new space set up for it. I have a similar problem in a bigger space and the competition between only two plants in there is causing problems for one of them at least. I'd say also that your lighting is quite ineffective also, it doesn't seem strong enough. In your shoes, I would create a second grow space from scratch or convert maybe a small wardrobe/closet if you know that the plants height won't get too extreme. If you need pointers on creating a grow space from scratch, I have a plethora of info regarding mine across my diaries. You're welcome to take a look. I've tried to be as informative as possible so hopefully if you're stuck for ideas, my experience (whilst still new) could be of use to you.

I'm in process to upgrade the lights but i don't have enough money to upgrade tent...

Your tent is only good for one small plant. Your light is also very minimal (I see total 37 watt CFL) even for one small plant. Upgrade your setup.

I would say to defoliate if u dont have no other option or tuck, start tucking some of those fan leaves and it can help with that. If u leave her like that u gonna start having issue's with humidity pockets destroying your leaves by creating moisture in betweenthem. Best of luck

If it's a thing of getting 3-4 Okay grown plants in your plant and lower underdeveloped bud, cause all the defol and LST won't help if you have grows at dif stages. Cause you can't scrog. II had a similar prob my tent was getting to packed with 5 nearly full grown autos. Before I knew it I was destroying my later staged plants with high RH made by lots of plants in a small tent, no matter the size my RH in my closed room went from 60 to 80% in my room not tent now, allall because I had too many plants in my room. Think of it like this. You can have 3-4 Okay grows. Or just focus on 2 if you don't have the space don't try cramming a plant in there for more bud it'll probably actually result in less bud. Idk what they are. But here's and idea. When it gets closer turn all your plants on a 12/12 and every 12hrs swap out your plants. If possible put the plants into your grow room with the blinds closed. Block out your windows and just rotate your plants. Its just an idea? Good luck bro.