Chuck,
Welcome to TFP.. A Great resource for anyone thinking about draining their pool...
If you plan to drain your pool for other reasons, that is fine, but if the only reason you are draining your pool is due to high Chorine levels, then that is just a waste of water.
Your FC (chlorine) levels will come down pretty quickly once you remove the tablets from your pool.
But the real question is... What is your CYA level. I say this because you do not have a clue if your FC is too high unless you know your CYA level first.
See this chart...
https://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock
Assuming your CYA is 100 you need at least 8 ppm of FC.. But the pool store will tell you 8 is too high.
The solution is to stay out of the pool store and start testing you own water.
Let us know if you are interested..
Thanks for posting,
Jim R.
edit.. to answer your questions, you do not need to move any valves to drain your pool, as the only real way to do it is to use a sump-pump, not the pool equipment.
I would also open the filter and clean it while the pool is empty. (Assuming you have a DE or cartridge filter)