Ed Turner is to leave Geronimo Inns after more than 15 years with the business.
Turner, who has been managing director of Geronimo Inns since April 2013, having joined the company in 1999, leaves with immediate effect.
Geronimo's owner Young's said it had restructured its managed estate operations and changed its senior leadership team.
The 36 managed pubs trading as Geronimo will now report to Patrick Dardis, Youg's retail director.
Geronimo will remain a separate division of Young's.
As a result of the restructuring, Turner agreed to step down from the board and leave the group.
"On behalf of the board, I would like to thank Ed for his contribution to the group over the last four and a half years, especially in his leadership of Geronimo since April 2013," said Nicholas Bryan, chairman of Young's.
Young's bought Geronimo, founded by Rupert and Jo Clevely, for £60m in 2010.