My mother was a hoarder. She used the room I shared with my brother until I was 13 as satellite storage for furniture and knackered bedding.
After he left, she started moving more furniture in, so I played dirty after she went nuts at me for suggesting I didn't need 2 beds, 4 mattresses, two sets of drawers, 2 wardrobes, a dressing table, 6 foot high shelves and a box that had been used to store whole cheeses in there when it meant I had to climb through a small gap to reach my bed.
I fucking trashed it. Trashed it to a depth of four foot, silently tipped over the precious fucking furniture and then waited.
Three weeks later, I came home from school to find that she was punishing me by emptying everything out of it other than one chest of drawers and a bed. Even the patch of see-through carpet had been torn up, leaving me with solid oak floorboards. And throwing a notebook at me listing every single item she'd thrown out, so I could 'suffer' some more.
I couldn't have been happier. Best move I ever made, that.
Anyway, my temporary pit was done deliberately to get her to the point of clearing the stuff I didn't want out of there, as the furniture was completely unnecessary and I felt that what should have been my space to keep out of her way was being used as another dump.
The OP's daughter might be a complete minger, or she could be deliberately trying to provoke a reaction to get rid of things she doesn't want - or just generally trying to provoke the OP for reasons unknown.
It's foul and needs to be gutted in order to be able to store normal amounts of teenage stuff. But it's worth asking the OP if she's angry about something/whether it's OK to chuck out the unnecessary furniture to start from scratch. Not as a reward, but because it's not well designed - it's easier to keep somewhere clean and tidy/more likely to happen if there is space.