Changing the markings isn't so much the issue, it's making (potentially dangerous) structural changes to the building without a permit. You can't put up something like that without certifying that it's done in such a way that it's not going to fall on somebody on the sidewalk and kill them.

(though according to the article it's for "design and safety" reasons, which sounds like maybe there are also rules about making visual changes to buildings, that you have to follow.)

In any case I don't know if it's Elon's property or not, there are a lot of places where he's renting (and not paying his rent, and getting kicked out)