I thought I'd like to share this since I didn't see any other threads.
I needed to remove the foam roadbed from pink foam that was glued with WS own foam tack glue. Here are my findings:
Use denatured alcohol. It works. Take a pipette and soak the roadbed. At first, I thought it would be best if I shaved as much roadbed as possible before applying the alcohol. It was not. It just made a mess. Pull up the roadbed up as a whole. Use enough alcohol to soak through. It helps to dig under the glue into the foam to get it started. Stretch the roadbed as you pull it up like you would remove those 3M sticky wall mounts.
I took a thin pallet knife and sharpened it on a stone to give it an edge. That helped out a lot because the handle was recessed.
Results will vary depending how you prepped the surfaces prior to gluing. It really makes a difference in adhesion by sanding the roadbed and the foam base.
I hope this helps someone.