How do I deal with clutter and mess caused by my husband?

My husband and I share a beautiful living/working space. He stores the remains of a former business plus he has his equipment for his current work in the space. I have the equipment and supplies for my current work. Our place is no longer beautiful. It’s a mess. His supplies are unorganised. We no longer have enough room. My husband holds onto things he hasn’t used in over a decade. I’m angry and frustrated. I don’t know how to deal with this mess and lack of space. He started throwing away items at the beginning of 2020, but covid lockdown put an end to it. How can I help him part with things he no longer uses? They are strewn all over.