"Deleted my Tesla titles last week to see what would happen. I'm now the Nothing of Tesla. Seems fine so far," Musk said on Twitter.
Tesla did not immediately respond to a request for comment.
While Musk is referred to as chief executive officer in Tesla's investor relations web page, his biography page on the company website has no designation. The biography page had earlier referred to Musk as chairman, product architect and CEO.
Musk later tweeted: "Legally required officers of a corporation are president, treasurer & secretary. Guess I have to keep 1st one or it will confuse the authorities."
Musk has agreed to pay a $20 million fine and step aside as Tesla chairman for three years to settle charges with the U.S. Securities and Exchange Commission related to his August 7 tweet about taking Tesla private.
However, in its initial lawsuit, the SEC had sought to bar Musk as an officer or a director of a public company.
Musk's compulsive tweeting and erratic behavior, which included smoking marijuana during a video interview, has raised concerns about his leadership, with several Wall Street analysts and some investors urging Tesla to appoint a strong second-in-command.
But the Silicon Valley billionaire shut his critics last week when Tesla reported a net profit, positive cash flow and wider-than-expected margins in the third quarter, delivering on his promise to turn the electric carmaker profitable as higher production volumes of its new Model 3 began to pay off.