A written statement from Norfolk Constabulary said: 'Philippa and the constabulary have parted company by mutual agreement. We would like to thank her for the contribution she has made while working for the force and we would like to wish her well in the future.'
Head of media services Simon Morgan is now acting comms chief. He is believed to have proposed a department restructure.
Winterburn, who was unavailable for comment, joined the force in 2004, and is believed to have previously worked for BT.
Norfolk Police has backed Home Secretary Charles Clarke's proposed merger of the Norfolk, Suffolk and Cambridgeshire forces, part of nationwide reforms.
Under the plan, opposed by Cambridgeshire and Suffolk, the comms functions of the three forces may merge. It could be a further reason for not replacing Winterburn.
But Norfolk and Suffolk Police Forces are opposing the plan to create a 'superforce', which the Home Office claims would put more officers on the beat and free-up cash.
Sixteen police forces are rallying to try and thwart the Home Office's proposals and have teamed up to create the 'Campaign for Local Policing' (PRWeek, 21 April).