Slory made just 11 appearances in the A-League for Adelaide United.
“Nobody can change my mind,” Slory said in a statement on Tuesday.
“I have thought about it and it has been playing on my mind for a very long time, and I have made a decision to go back to my family and friends in Holland.”
Slory admits he is thankful for Adelaide coach and fellow Dutchman Rini Coolen, who brought him to Australia.
“I owe a lot to Rini for getting me to Australia because he wanted me to come here and help me to get my love of the game back,” he said.
“Now I just want to go a different way.”
