What does everyone do to winterize ATL tanks when there is ethanol involved?

I pumped out all of the remaining fuel and used it in my pickup! Before doing so, I added some Sea Foam to treat the little bit of fuel that would be left over.

I would try and remove it. Ethanol fuel has some corrosive properties. They do make Stabil that is specially formulated for Ethanol if you can't pump it out.