Martin Healy, the acting chief executive of Threshers owner First Quench Retailing, is to leave the business.
The company, which operates 1,400 stores under the Threshers, The Local and Wine Rack fascias, said Healy had resigned to "pursue other business interests".
The former finance chief took up the reins in August on a temporary basis when former boss Yvonne Rankin stepped aside due to ill health.
Johan Van de Steen, who was last month named as the group’s new chair, steps up to become executive chairman. First Quench has also named Martin Boden as its new chief financial officer.
The group recently appointed former Somerfield chief operating officer John Cleland as a non-executive director to its board.