For decades, Mr. Landesman, 67, had been a pillar of the international art scene, a man-about-town known from the galleries of Manhattan to the Art Basel fair in Switzerland for his primary-colored suits and deep connections in the industry. The brother of the renowned Broadway producer Rocco Landesman, who once served as the head of the National Endowment for the Arts, he started at Artforum in the 1980s and until Wednesday had run the magazine with his three co-publishers, Anthony Korner, Charles Guarino and Danielle McConnell.

The lawsuit that preceded his departure was filed in State Supreme Court in Manhattan and included accusations that he had harassed nine women, groping them, attempting to kiss them, sending them vulgar messages and, on occasion, retaliating against them when they spurned his advances. The accounts were from both former employees at the magazine and women Mr. Landesman met at art events, all of whom said he took advantage of them at “the start of their careers” when they were “economically and professionally vulnerable.” The suit also accused the owners of Artforum, one of the art world’s premier publications, of being aware of his behavior but doing little to stop it.

The only named plaintiff in the suit is Amanda Schmitt, a New York curator who started working at Artforum in 2009 when she was 21. Shortly after Ms. Schmitt took the job, the suit contended, Mr. Landesman “singled her out for unwelcome sexual attention,” subjecting her to questions about her sex life while “touching her, uninvited, on her hips, shoulders, buttocks, hands and neck.”

Ms. Schmitt left Artforum in August 2012, but two weeks later, after she had started a new job in sales, Mr. Landesman sent her an email, reviewed by The Times, in which he praised “brown nosing” as a sales technique before veering off into a different — and sexually explicit — description of the practice. Not long after, Mr. Landesman invited Ms. Schmitt to tea, ostensibly to discuss her career, and grabbed her by the shoulders, trying to kiss her, the suit said. It also cited another incident in which Mr. Landesman is said to have told Ms. Schmitt that she needed to be “more open to physical contact to succeed” and demonstrated by running his finger down her body.