The Swiss goalkeeper was one of the more impressive performers in 2019-20, in what was a frustrating season for the Wanderers.
The 35-year-old kept three clean sheets and conceded 33 goals in 22 matches for the Wanderers.
Unless the club signs a replacement, new Wanderers coach Carl Robinson will have to rely on either Vedran Janjetovic who is coming off shoulder surgery, or 23-year-old Daniel Margush who recently started in goals for the Wanderers in a friendly against Adelaide United.
Lopar's departure also frees up a visa spot for the club.
