Is there a possibility to remove the iron/plastic skeleton parts of the roof without damaging a textile so it is easy washable in the washing machine?
In theory, it is kind of possible, but very hard and just for people to understand how it is put together. So I will rather say no, for a normal mum or dad, it is rather hard and even if you manage it, you might end up not being able to put it back (always record your removal, so you can go back to how it was, btw).
Anyhow, the washing machine is not really friendly for stroller hoods as they fade easily. If you want the hood to be made by a tailor, you can (or she can) cut it out and sew a new one with zippers. And if you need to clean your canopy, read THIS article about cleaning your stroller, there's a part about cleaning a canopy, too.