Cumming, 26, has offers on the table from both the Power and Crows but has been more heavily linked to the latter.
He has yet to confirm a preferred destination, but days after the Giants' season ended in heartbreaking fashion, Cumming, who hails from Broken Hill, told the club he wanted to head to South Australia.
"Wingman Isaac Cumming has informed the club of his decision to explore his options as an unrestricted free agent," the Giants said in a statement.
"The Broken Hill product played 81 games for the club over eight seasons and will explore free agency options in South Australia."
Cumming, who also had an offer to stay on the table from GWS, is expected to be one of several Giants to depart.
Fellow free agent Harry Perryman, 25, has been heavily linked to Port Adelaide, along with Hawthorn, but appears more likely to join the Power.
Veteran defender Nick Haynes, 32, is widely expected to join Carlton.
Harry Perryman is also set to leave the Giants. (Joel Carrett/AAP PHOTOS)
Cumming was originally part of the Giants' academy.Â
He can play on both the wing and in defence but managed just six games in 2024 due to a run of calf and hamstring injuries.
As an unrestricted free agent, Cumming can move automatically to the club of his choice when the free agency window opens on October 4, but the Giants could receive a compensation draft pick.
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