Provision may be made that should any member who either (1) has not less than 25 years of credited service, or (2) has attained an age not less than age 50 years and has not less than ten years of credited service, and in either case leaves city service prior to his voluntary retirement age, for any reason except to retire with a pension payable from funds of the retirement system or his death, he shall remain a member for the exclusive purpose only of receiving a pension upon his application therefor filed with the Board on or after his attainment of age 65 years. In the event such member withdraws all or part of his accumulated contributions from the pension savings fund he shall thereupon cease to be a member and he shall forfeit his right in and to a deferred pension.