Generally there are rules for what can be placed as a sign on a building.

It also goes into detail in the article.

I assume you need permit for such a large installation, for safety reasons. Design on picture is one thing but you need to make sure it will stand safely on the roof and not fall on people's heads

Elon's renting the building, they violated city ordinance a few days ago by trying to remove the Twitter logo without permits.

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)

In general you are not allowed to make changes to your property in ways that may endanger yourself others. For bigger changes, bigger properties, and properties that are more urban you often need permission from the city on more things. But even when building things for a home out in the suburbs you will often need the correct permits.

This is not exclusive to American law.

First, the city "owns" all the land everything is built on. If the city doesn't like something, they just eminent domain your shit and change it. Second, a lot of old buildings in SF are "historic" buildings, which is a legal classification that means either the building itself or an event in the buildings past has enough historic value to preserve for future generations. This means the building is protected from change in a whole bunch of very complicated and specific ways. Replacing a sink faucet or light fixture generally takes months of inspections, board review, and other bureaucratic nonsense. I can't imagine the amount of work that was supposed to have been done before either the old sign was taken down or the new one was put up, but I'm pretty sure muskymoo didn't bother.

idk anything about US property laws but im pretty sure he just missed the how to break property laws day in sociopath daycare