My dog keeps destroying his beds/ cushions when left alone, what can I do?

A crate! They work wonders. Both of my dogs ate everything when they were puppies, I started crating them when they were alone and it helped so much. I don't have to lock either of them in the crates now that they are older, but they still love the crates enough to sleep in them all the time(I just leave them open in the living room). If he tears up blankets in the bed, take them out for the few hours you are gone. It won't hurt him to sleep on the hard floor for a little while, and prevents him from tearing anything up.