The platform, which is popular with the US far right, went offline last month, but has since partially returned.
The chief executive of Parler, the social media platform favoured by far-right groups, said on Wednesday that he had been fired.
John Matze said he was removed by the company last Friday.
"On January 29, 2021, the Parler board controlled by Rebekah Mercer decided to immediately terminate my position as CEO of Parler. I did not participate in this decision," Matze wrote in a Memo to staff, originally reported by Fox Business.
"I understand that those who now control the company have made some communications to employees and other third parties that have unfortunately created confusion and prompted me to make this public statement."
Parler, founded in 2018, labels itself a “free speech” platform and had seen a rapid growth in - mostly conservative - users amid a crackdown on misinformation and hate speech from other social media sites.
However, the app was taken offline in January after Amazon cut off their web hosting services, citing content moderation failures following the attack on the US Capitol by a pro-Trump mob.
It followed a decision by Apple and Google to remove the app of their respective app stores.
The site has since partially returned online with the help of a Russian-owned technology company.
It was announced this month the FBI would be investigating the role of Parler in facilitating and coordinating the attack on the US Capitol.
