Referring to himself occasionally in the third person, he told the Deciem staff that “my love and respect for you is immense” and asked that they pay close attention to “the communication that DECIEM will share with our world during the few weeks and months ahead of us.”

Stephen Kaplan, formerly Deciem’s chief financial officer, left the company in February. He said in an email Wednesday that he had resigned “because Brandon’s demeanor had changed following a December vacation in Mongolia.”

Mr. Kaplan said that he had “no interest in all the current drama.”

“I feel sorry for all the staff that must deal with Brandon on a day-to-day basis,” he said. “Until he changes his ways, he is destroying what could have been a very successful company.”

An investor in the company indicated that it was also troubled by Mr. Truaxe’s behavior.

“The Estée Lauder Companies is a minority investor in Deciem, and, as such, we do not control the company’s operations, social media or personnel decisions,” said a spokeswoman for Estée Lauder Companies. “We are deeply concerned by the material that has recently been posted on social media and will defend our rights as a minority investor.”

Mr. Truaxe answered his phone on Wednesday but hung up when a reporter asked permission to record the call; following calls went to voice mail.

The Instagram video this week apparently signaling the end of Deciem sent many of the company’s customers into a frenzy as they sought to understand whether their preferred products would remain available. Many of the company’s New York stores were closed on Tuesday afternoon and its website indicated that almost all its stores around the world had been shuttered, including ten locations in Canada and four locations in the U.K. (Only its three stores in Mexico City were not marked as closed.)