Elon Musk said he was about to make one of the most visible changes to Twitter since he took control of the social media company last fall: replacing its widely recognized bird logo.

In a tweet early Sunday morning Eastern time, Mr. Musk said that “soon we shall bid adieu to the twitter brand and, gradually, all the birds.”

He added shortly after, “If a good enough X logo is posted tonight,” it would “go live worldwide tomorrow.”

“X” is a term for what Mr. Musk has described as an “everything app” that could combine social media, instant messaging and payment services, akin to the popular Chinese app WeChat.

Mr. Musk has said that buying Twitter is “an accelerant to creating X,” and the corporate entity he created to purchase and control Twitter is called X Holdings.

Mr. Musk spoke on a Twitter audio livestream early Sunday to say he was changing Twitter’s logo. “It should have been done a long time ago,” he said. “Sorry it took so long.”

A few hours later, Mr. Musk said in an email to Twitter’s employees that “we are indeed changing to X” and that it was happening “today.” “This is my last message from a Twitter email,” he wrote, before signing off with a salute emoji.

Mr. Musk has few barriers to making such alterations at the company after taking it private as part of his acquisition of the firm. But he could still encounter resistance from the banks that have lent him billions of dollars and the private investors he brought into the deal, who could raise concerns about jettisoning one of Twitte