All she needs is hay and water unlimited, and pellets are only a supplement, you can reduce them to one tablespoon a day or you can keep her on hay only for a week or so, you will see that there's no smooshed poos in the mornings anymore.
I am no vet but yes I think that her diet caused her kidney problems, and I wouldn't cut on greens (except those high on calcium and oxalates like kale) but I'd definitely cut on pellets and would transfer her slowly to non alfalfa pellets with more fibre and less protein.
You can start from reducing her pellets to half, then to half again, she will probably eat all of them and will be looking for them, then you can start mixing some new (13% protein, 19% fibre, non-alfalfa) into her old, do not remove her bowl on refill until it is empty, she will eat some when she's hungry. I think you simply overfeed her and she eats only what she likes best, don't stop feeding her abruptly but reduce pellets and let her eat other foods, she should start eating more hay then, which is very positive thing. Hay must be unlimited and it makes 80% of her healthy diet. For now she has too much protein rich food, you want to change it if you don't want further health problems. Greens are not fat and she can have them, limited. Pellets need to be reduced and slowly changed to other type suitable for her age and needs.