Water/Avgas/Gasahol/Mogas

Jim Weir wrote
Two years of college chemistry does not a chemist make out of me

You're not asking a chemistry question, you're asking a chemical
engineering question. Not the same thing at all. Anyway, I happen to
be one.

is there a cheap and easy way to chemically (or mechanically) take the alcohol
out of gasoline?

Yes. Extraction. Mix gasoline with equal quantity of water, agitate
(shake or stir), let sit in cool place. The alcohol will (almost) all
be in the water phase on the bottom. Drain water off bottom.
Gasoline is ready to use.

Your problem is the water. It now has a few percent alcohol, and
traces of organics from the gasoline. Can't just toss it (legally).

You need to flash off the alcohol and organics. Fill jug with the
water, stopper it but let a tube come out. Warm to 180F, give or
take. This will drive off some gases, which you can feed into a small
flame (a candle will do). When the water level goes down a few
percent, you're good. You can reuse that water for the next batch.

Michael