Whiteside will be replaced by Yvonne Rankin, formerly chief executive of global retailer AS Watson.
Scott Greenhalgh, managing director of Vision Capital – which acquired a majority stake in Thresher Group in June – said: "On behalf of the entire management and staff I would like to thank Roger Whiteside for his service to the Thresher Group. Roger has steered the Thresher Group through a period of significant industry change and we thank him for providing a smooth transition to our ownership. We look forward to working with Yvonne Rankin in the next stage of Thresher Group's development."
Rankin said she was looking forward to "working with the team to strengthen its position as the leading independent specialist drinks retailer in the UK and improving our customers' overall experience".
Since joining the Thresher Group in April 2004, Whiteside has overseen the transformation of the business into three clear fascias – Threshers, The Local and Wine Rack. The Local convenience shops were rolled out in 2004 and the Wine Rack fascia was rejuvenated in 2005. His tenure also coincided with the launch of three-for-two and the purchase of 200 shops from Unwins.