What should the shed be painted with?

In a multi-family house, I have this shed system.

Something needs to be done with the shed. The lower part is now always green, which is not easy to wipe off. How should one proceed here to protect the wood? How do you remove the green and which paint is then recommended?

I would mechanically remove the weathered parts, maybe with a wire brush. If it is already soft, it cannot be hardened again, so you don’t have to sand through until nothing is left. There are transparent primers that are fungicidal, etc., I would use those as a primer. They even exist in organic versions. The coating could be a thick-layer glaze. Look closely, if you can see the grain through it, it’s a glaze. If it is completely opaque, then it’s a paint. Thick-layer glaze is in between. I would stay with the same material that is already applied. Clean thoroughly, let dry, and sand very lightly. Fine grit, just like scrubbing. I cannot detect any significant cracks in the coating. If you want to preserve the lower edge longer, and the rest still looks good, you could put a metal strip as protection into the sound material.
Best regards Gabriele