The former Leeds and Liverpool star famously fell out with the fans' favourite during his time at the Broadfield Stadium and the midfielder left the club.
The former Leyton Orient hero's contract, which was due to expire in June 2019, was terminated by mutual consent.
Cox, who was signed by Dermot Drummy, made 27 appearances for the Reds, scoring two goals, but was left on the sidelines by Kewell. Cox is now at Eastbourne Borough.
At the time, the midfielder tweeted: "Last season wasn’t what I wished, however I would like to thank the fans for their support and wish the club all the best. Looking forward to a new season wherever that may be."
But soon after the news broke today about Kewell, he tweeted: "What goes around comes around."
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