I guess I woudn't just for the simple fact that I just wouldn't. But there are water soluble foundation paper out there. Just google it. You don't have to remove it and it will dissappear in the wash.
Here's one by Sulky but I know I have seen others.
http://www.amazon.com/Sulky-Paper-So.../dp/B002LN1CJ2
Carol Doak (Queen of Paper Piecing) has her own line.
http://www.joann.com/carol-doak-s-fo...-pkg/prd34221/