According to the filing, Munoz asked for his employment agreement to be amended insofar as his future appointment as chairman of the board of directors is concerned, "leaving future determinations related to the Chairman position to the discretion of the Board".
Munoz said this week that Dao's treatment was "humbling" for United and accepted full responsibility.
The CEO of United Airlines has asked for more time to give USA senators a full explanation of why a passenger was forcibly dragged off a flight, prompting national outrage.
In a letter to the senators, CEO Oscar Munoz said United Continental Holdings Inc. needed until April 27 to thoroughly investigate the matter and review policies including how it handles "oversold situations".
The move comes almost two weeks after a United passenger was violently dragged off a flight in order to make room for airline personnel.
Earlier this month, an elderly United passenger, Dr. David Dao, was dragged from his seat off a parked plane at Chicago's O'Hare International Airport bound for Louisville, Kentucky, to make room for crew members. No passengers voluntarily agreed to cash payments to give up their seats, and the airline then chose four passengers to be taken off the plane.