I’ve had good luck using diluted Nature’s Miracle carpet shampoo, combined with an oxygen carpet booster. I make a dilute solution, squirt some on, allow to soak for a few minutes, then blot dry. I used to use white vinegar, but I found my bun kept remarking the area. She has been less likely to with this combo.

The nature’s miracle solution is also pretty good, but they changed their formula recently and the fragrance is super strong now (and I think the product is less effective). I like the shampoo version better, you just have to dilute it a lot.

Keep bun away from the area until it’s dry. You also might end up needing to block her access to that area, or put a litter box there. Unfortunately buns like to pee on soft things, and once they pick an area to pee in, it can be hard to convince them otherwise (it is possible though!).