You just bought abrand new Softub model220 dealer told you to cut off bottom solid foam and squish it down if you wanted to get it into your cellar bulkhead Has anyone ever done this?

I haven't done it, but I seriously doubt it could be repaired once cut. Look for the manufacturerer's phone number and call them and ask them if it's ok to cut the bottom and how to repair it after. I would expect that they would tell you not to, after they stop laughing.