How to hide/remove this foundation?

"ClaimingTheFifth;15166063" wrote:
From what I can tell by your pic - just move the foundation slider all the way down. If you don't like what happens you can always reverse the action with the undo arrow at the top of your screen. My best guess is that all it will do besides removing the foundation is kick out your stairs which are easy to replace.

I can't just remove the foundation entirely. I should mention it's necessary for the front porch (which is just raised up slightly like a patio rather than a proper porch). I probably should have included that in the first post. Anyway, I only want to remove the foundation where it appears behind the house.