I removed carpet and old floor tiles from basement floor and I was looking for a good way to clean all the old mastic and glue that was on the floor. Any good ideas?

Anytime I clean anything at my home with glue, fiberglass, etc, that needs to be broken down, I use Acetone. Can be bought by the gallon at any paint store, lowes, etc, good to clean your hands and paint brushes also. Anything that breaks down fiberglass will definitely break down glue.

Acetone is extremely flammable. KABOOM!! There goes your house. You won’t have to worry about adhesive on your basement floor any more. You might as well be using gasoline. Your basement probably contains a gas furnace with a pilot light that is constantly on. Your basement probably contains a gas water heater with a pilot light that is constantly on. So, you might have two constantly burning small fires in an enclosed space (your basement). DO NOT USE FLAMMABLE SOLVENTS. Acetone is a solvent. Even if your basement does not have a gas water heater or a gas furnace, it has light switches. They sometimes spark when they are turned off and on, and they can set the flammable solvents off. It is winter and you might pick up static electricity that can spark and set off the fumes. Did you ever hear of people accidentally setting off an explosion at a gas station in the winter when they started to go back into their car to stay warm? It was static electricity that did that. Acetone evaporates rapidly. If you use enough, you will be overcome by the fumes and pass out. In that case, you might not notice the explosion when your house goes up. You must use something that is not flammable. You have been warned.

Rather than removing old glue/ mastic on floor, I believe most pros will skim coat with thinset floorpatch to smooth/ level

I have the same problem and I have opted out of using any chemical removers; but I AM extremely interested in this “thinset floorpatch” stuff to smooth and level the floor. Can you tell us more about it?