Unfortunately, there is no reliable "chemical neutralizer" for CYA that you can just pour into the water. Here are the three ways to handle it, ranked from most to least effective.
1. Partial Drain and Refill (The Gold Standard)
Since CYA stays behind when water evaporates, the only way to physically remove it is to remove the water itself.
The Process: Drain about 25% to 50% of your pool water and refill it with fresh water from a hose or truck.
Caution: Never drain a pool completely without professional advice, as the "hydrostatic pressure" of the ground can actually lift an empty pool shell out of the earth.
2. Reverse Osmosis (The High-Tech Option)
If you live in a drought-prone area where water restrictions prevent draining, you can hire a service that uses a Reverse Osmosis (RO) filtration trailer.
Pros: You keep 90% of your water; it removes CYA, calcium, and salts.
Cons: It can be expensive and isn't available in all regions.
3. Biological Reducers (The Hit-or-Miss)
There are specialized "CYA Reducer" enzymes on the market.
The Reality: These are very finicky. They require specific water temperatures and zero chlorine levels to work. Most professionals find them inconsistent compared to a simple drain-and-refill.