Galvin blamed work and travel commitments for leaving the role after 16 months.
Three wins in the spring had seen Galvin lead Wexford to second place in Division Four of the Allianz Football League.
Galvin said in a statement that he had moved back to the west of Ireland due to the Covid-19 pandemic.
He thanked the Wexford County Board, they players and his backroom team, saying "I have a strong belief in the talent in the county".
Senior Football Update - Statements from Paul Galvin and Wexford GAA: pic.twitter.com/s4VU6ViAm7
— Wexford GAA (@OfficialWexGAA) September 15, 2020
The county board responded to Galvin resignation with a statement saying: “It is with regret that Wexford GAA has accepted Paul Galvin’s decision to step away from the role of senior football manager and we wish him the very best of luck in his future endeavours.
“Wexford GAA would like to thank Paul for his commitment and dedication over the past 16 months as senior football manager. It is without doubt that Wexford football is in a much stronger position thanks to his efforts during this time."
Former Wexford player, Roche was a member of Galvin’s backroom team.