In a statement Morgan said: "I have been informed that Morgan has rejected my appeal and, as a result, I have been removed from Morgan Technologies.
"It is incredibly disappointing news for my family and myself. We remain very grateful for the expressions of support received from Morgan fans, workers and the public since this process began."
According to documents seen by Autocar, he was fired from Morgan on four counts of misconduct, including posing as chairman despite being demoted to strategy director.
"I have been dismissed on what I believe are very contentious grounds. Over the last 12 months, it was made increasingly clear that my philosophy to modernise Morgan did not fit with the philosophy of the current management," continued his statement.
"My view is that Morgan’s future cannot rely on its heritage alone. As such, I endeavoured to introduce our unique brand to new markets such as China; to take Morgan racing again; and to engage the passion of a new generation using social media, and by doing interesting things such as the Gumball Rally in a 3 Wheeler.
"My aim has been to give Morgan a bright future as an independent company. My record in business is something I look upon with pride – volumes doubled during my tenure and profits for the first six months of the year had increased dramatically to £1.2 million.
"I remain a major shareholder in the Morgan Motor Co and am concerned for its future. I will take time to consider my next actions and potentially explore other opportunities available to me."
Morgan was replaced as managing director of the firm in March, with then operations director Steve Morris taking the helm.