Remove some or all of the water
Remove some of the water and refill it with fresh water.
Remove some water in container (10-20%) and add new water. example: pump water high in cyanuric acid out of a swimming pool and the add fresh water to the pool.
When we had a baby pool, we carefully lifted the side of the pool and dumped it into the yard. If the side was too heavy to lift enough to begin draining, we could use a bucket to remove some of the water weight first.
No. Boiling water kills bacteria but does not remove most chemicals.
Pool water needs to be regularly sanitized with some sort of system that kills bacteria and other pathogens. Then the water needs to be run through a filter to remove dust and bio materials to keep the water clear
Scrub it down with fresh water and a stiff broom or brush
You should remove the antifreeze with a shop vac if possible, antifreeze will not hurt the water, but is just one more thing in the water that you do not need to be there.
You will have to drain some or all of the water depending on how much TDS you need to remove.
Keep your pool water clean is a very challenging task. You can use some pool supplies like Dust Net, Water filter, water vacuum cleaner for remove dust from surface, etc. Keep switch on your water filter for 24/7 hrs for cleaning water or remove small dust particles from the water. Clean your water filter after every 7 days it makes clear passage through the filter, it helps your water clean regularly. If you do not clean your filter then your filter get chocked up and water will not pass through the filter. You can chlorinate you pool water it also help to keep your pool water germs free.
Baking soda will not soften (remove calcium hardness) from pool water. It will raise total alkalinity.
A pool filter is there to remove particles of foreign matter from the pools water. Without a filter to remove this material it would not take long for the pools water to become cloudy and dangerous to the health of the swimmers.