Purse started 17 of the Valiants' last 20 games to help them secure a first promotion in 19 years after joining the League Two club on a free transfer from Plymouth in January.
However, the 36-year-old centre-half is to leave Vale Park along with fellow defender Clayton McDonald, midfielder Kingsley James and striker Calvin Andrew.
Manager Micky Adams has offered deals to 10 other players whose contracts are set to run out this summer.
Goalkeeper Sam Johnson, left-back Dan Jones, captain Doug Loft, midfielder Sam Morsy, winger Ashley Vincent and striker Ben Williamson have been offered two-year deals.
Defender Adam Yates and midfielder Louis Dodds have been offered one-year contracts with an option for a second year, while midfielder Chris Birchall and defender Liam Chilvers have been offered 12-month deals.
Veteran striker Lee Hughes, who originally signed until the end of the season, has another year on his contract which has been automatically triggered by the club's promotion to League One.