He also sought to reassure employees that Univision would stand behind Gawker Media posts going forward. “Should there be threats in the future related to stories published on our Gawker Media Group sites, no matter the date of publication, we will defend them as vigorously as we would defend stories published by Univision News, Fusion, The Root or any of our other properties,” Mr. Lee wrote, adding that the decision to remove the posts was “not a precedent for the future.”

The deleted posts include two that were published by Gizmodo in 2012 about the claim by a man named Shiva Ayyadurai that he had invented email. Mr. Ayyadurai filed a lawsuit this year against Gawker; Nick Denton, the company’s founder; and two Gawker journalists, Mr. Cook and Sam Biddle, contending that articles that cast doubt on Mr. Ayyadurai’s claims were defamatory. Charles J. Harder, who represented Mr. Bollea in the lawsuit against Gawker, is representing Mr. Ayyadurai in the lawsuit. It is not clear if Mr. Thiel is providing financial support for the case. (Mr. Harder is also representing Roger Ailes, the former chairman of Fox News, in potential litigation against New York magazine, and Melania Trump, the wife of the Republican presidential nominee, Donald J. Trump, in a libel lawsuit against The Daily Mail.)

Other Gawker Media posts that have been removed include two about Mitch Williams, a baseball analyst and former major league pitcher; one about a conservative blogger; and another that called a man acquitted of sexual assault charges a rapist.

In place of the posts, a note reads, “This story is no longer available as it is the subject of pending litigation against the prior owners of this site.” The comments about the original post remain.

In his memo, Mr. Cook wrote that the posts would be removed under a provision in Gawker’s collective bargaining agreement that states: “Once a story has been posted, it can only be removed by a majority vote of the executive editor, the C.E.O. and the general counsel, unless required by law.” The provision was written into the contract between Writers Guild of America, East, and Gawker Media when Gawker Media’s editorial employees unionized, before Gawker put itself up for sale.

The guild said in a statement on Saturday that it was “deeply troubled” by the decision to remove the posts.

“Though Unimoda has offered assurances that it is committed to robust, fearless journalism, this move seems to belie that claim,” the guild said. “The decision to remove these posts casts a significant pall over Unimoda’s claimed commitment to the core values of our members employed by Unimoda.”