Why do you want to drop the chlorine level? If you are done swimming for the season, I say leave it and see what it does. Don't put anything else in it, monitor your levels as you are doing, and only add what you need to maintain chlorine and pH. You don't need the tabs because they probably have CYA in them. When the weather starts getting better in the spring, start the drain and refill process until you CYA is down and go from there.