An inspector from the city's urban planning department who came to investigate the metal structure was denied access to the building on Friday and Saturday, according to an official report.
A company representative, however, told him that it was a "temporary illuminated sign for an event".
At night, the structure lights up with bright lights. Interviewed by local television stations, residents of the neighborhood complained of a level of brightness as in broad daylight, to the point of being dazzled.
A week ago, Elon Musk renamed Twitter "X", a mathematical symbol he likes and found in SpaceX, one of his companies, and the name of one of his children, a boy named "X Æ A-XII", or "X" of his diminutive.
The owner of the social network wants to turn it into a platform to do everything on the model of WeChat in China.
"X is the future state of unlimited interactivity — centered on audio, video, messaging, payments/banking — creating a global marketplace for ideas, goods, services and opportunities," said the company's new chief executive, Linda Yaccarino.
But the billionaire has encountered several obstacles with the city of San Francisco, which already intervened last week when workers removed the letters of the original sign on the edge of the building. Some of it is still in place.
"I explained to all the representatives [of the group] that the (X-shaped) structure had to be removed or submitted for approval," the inspector said in his report.
"Many people have made us tempting offers to move the headquarters of X out of San Francisco, especially since the city is engaged in a tragic spiral where the departures of companies follow one another," Elon Musk said on the social network Saturday. But "we will not leave," he promised. His profile displays a photo of the X illuminated on the roof.
At the end of 2021, Elon Musk moved the headquarters of his flagship, Tesla, to Texas, a state with flexible taxation and a lower cost of living. He had clashed with California authorities over the mandatory closure of the plant at the beginning of the pandemic.
Last winter, his lawyers tried to move a fraud trial from San Francisco, Texas, saying an impartial jury could not be assembled in the Democratic city.
© 2023 AFP