The Welsh striker was told last week by Argyle manager John Sheridan that he was surplus to requirements and has been released from his contract in order to seek first-team football.
Rhys, 32, joined the Pilgrims from Welsh Premier League side Port Talbot in August 2012, having won the league’s golden boot award for seven consecutive seasons.
He made his debut as a half-time substitute against Northampton Town in September and had been on the pitch just 12 minutes before he scored his first goal.
In all, Rhys made 17 appearances, 10 as a substitute, scoring three goals.
Everybody at Home Park wishes Rhys all the best for the future.