How do you remove cam bearings on a small block Chevy?

The first step is to buy or rent a cam bearing installation tool. Check your local auto parts store. It should come with instructions, but you will probably need to take the engine completely apart in order to be able to get the old bearings out after you drive them through to an open space. There's not enough room to reach up in there and get them out with the crankshaft and rods in the way.