Olins, who set up Wolff Olins with Michael Wolff in 1965, is understood to be leaving to work independently as a brand consultant. Michael Wolff left to set up his own consultancy in 1987.
Last month, Omnicom bought the consultancy for an undisclosed amount -- believed to be in the region of £30m -- and formed a new board of directors.
The London-based company's client list includes 3i, Orange, Diageo, Tesco, Channel 5 and the World Gold Council.