The FTSE 100 listed group - set up in 2008 to consolidate the life insurance industry - wants to drop the Resolution name in favour of its Friends Life brand and will ask shareholders at its annual meeting in May to approve the move.
Mr Cowdery's decision to step down from the board marks an end of an era for the group, although he had already taken a back seat by becoming non-executive director and will retain his 0.6% stake in the group.
The firm also announced fellow non-executive director and former Financial Services Authority chief executive John Tiner would also leave the board. They will sit on an "advisory" committee that will allow the firm to "share views regarding the future direction of the company".
Mr Cowdery said the group had "delivered on its targets", having made £160 million of cost savings under its three-year overhaul.
Friends Life now wants to establish itself as a key player in the UK pensions market under a "new and exciting chapter", according to group chief executive Andy Briggs.
Details of the changes came as its Friends Life brand reported a 53% rise in pre-tax operating profits of £461 million..