Anyone know how to lower alkalinity in pool?

Acid, either muriatic or dry acid. The trick is how you add it. Turn the pump off so the water is still, and pour it slowly in one spot in the deep end so it sits in a concentrated pool. That knocks the alkalinity down more than spreading it around. The pH will drop too. Bring that back up by aerating the water, point the returns at the surface, run a fountain or a hose spray, which raises pH without putting the alkalinity back. Repeat over a few days until you're in range. Read the dosing on the acid label, and always add acid to water, never the other way.