According to that point of view the laptop and the OS form a common entity that cannot be taken apart without destroying the product.
As a result you can still refuse to accept the Windows EULA, ask for a refund and the seller will ask you to return the product to grant you the refund. The problem is, the product is the "integrated device" and not some "OS part" so you'll have to return the laptop too.
Storage is limited as you mentioned but it can be expanded with an SD card.