Leave the water in the pool until you're ready to repair the wall. The water supports the pool, and draining the pool can cause the wall to collapse further. If the wall collapses after the pool is winterized and the water is frozen, remove any snow from the cover. Wait until the temperature remains above 32 degrees Fahrenheit and all the ice in the pool is melted.
Drain the water, following the directions in your pool owner's manual and acting in accordance with your city's pool draining rules. Each city has pool-draining regulations, and usually the pool must be drained into a sewer clean-out or drained slowly into your yard. Pools cannot usually be drained into the street or an alley.
Remove the pool walls and the liner, based on the manufacturer's assembly directions. Once the wall is collapsed, it can't be repaired. Replacement is required.
Contact the pool dealer to obtain replacement parts. Replace the pool with the new parts, based on the assembly instructions.