The app, which was popular with Donald Trump supporters, was taken offline and effectively shuttered by tech giants in the wake of the Capitol violence on 6 January.
John Matze told his employees in a memo that he had been removed by the company’s board of directors and insisted that he “did not participate in this decision”, reports the Wall Street Journal. He said the board was currently controlled by Ms Mercer, the 47-year-old daughter of hedge fund manager Robert Mercer and a prolific donor to the GOP.
“Over the past few months, I’ve met constant resistance to my product vision, my strong belief in free speech and my view of how the Parler site should be managed,” Mr Matze said.
“For example, I advocated for more product stability and what I believe is a more effective approach to content moderation.”
Parler had an estimated 15 million users and became popular with conservatives in the months following Mr Trump’s election defeat to Joe Biden.
Many users were attracted to the app after other social media platforms took action against the false claims made by Mr Trump that the election had been stolen from him.
Parler did not allow threats or criminal activity but was only moderated by part-time “jurors.”
It saw a huge spike in downloads following Donald Trump’s social media ban by Facebook and Twitter, but was closed down when Amazon Web services kicked it off their servers following the Capitol attack.
Mr Matze told his former colleagues that he would take a few weeks off before deciding what to do next.
“After that, I’ll be looking for new opportunities where my technical acumen, vision and the causes I am passionate about will be required and respected,” he wrote.
“I want to thank all the people of Parler that supported me and the platform.
“This has been the true American Dream: an idea from a living room to a company of considerable value. I’m not saying goodbye, just so long for now.”
Ms Mercer is the daughter of hedge-fund tycoon Robert Mercer, who has financed a string of conservative causes and spent $25 million helping Donald Trump win the 2016 election.