I live on Long Island, NY and have gotten many differing opinions from local pool companies on water level for pool closing over the years.
Some say there is no need to lower the water level. Just blow out and plug return lines, blow out main drains and blow out skimmers with gizmo. They state the positive is the pool cover is supported by the water under it and does not sink in. And my stairs are vinyl and the top steps tends to pull away from the side when the water level is dropped. Stating this is another reason to not lower water...less potential damage to top step.
Others say just below the skimmer basket to prevent water from freezing in the skimmer and getting into the lines. They still do the same blow out procedure as not lowering the water level.
And the extra cautious say, lower it below the returns. This would be really low in my pool. Maybe a 50% drain.
What is recommended for my region of the country?