Candace
I have to scrape them out frequently on the Featherweights that I service. There is a screw in each of the rubber feet. Once you get all of the old rubber piece out; take the screw out and install the new bed cushion, put the screw back in and tighten it.
Make sure that you get it all out or the new one won't fit right. The link below is where I get things like that for the Featherweights.
www.221parts.com
Sharon W.