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Polenz is the latest player to leave the Queensland club after the departures of star midfielder Carona, rising defensive star James Donachie and the retirement of former Australia player Shane Stefanutto.
After signing with the Roar halfway through the 2014-15 Hyundai A-League season, the German defender made 12 appearances for the club.
The 29-year-old spent two seasons with the Western Sydney Wanders and was a starter in their inaugural match before signing with Norwegian club Sarpsborg 08 FF for half a season in 2014.
In a release on the club website, Brisbane Roar thanked Polenz for his contributions during his two years with the team.