No, they can't. They are programmed by Mercedes-Benz at the key and lock facility. They are programmed with data from the MB master computer which has all the codes for all the possible keys for all MB's utilizing this technology.
Possibly MB "could" do it, but they likely would refuse. I don't even know how you would ask them. The dealer can't. We can't do anything which would affect the key itself. What we can do only affects the car itself. We can "block" a key to keep it from working, if for example a key is lost or stolen. We can later go in and "unblock" a key, although in some cases it requires a special "download" key from the lock and key facility to reauthorize a key.