McAsey, the No.6 pick in the 2019 draft, had been on personal leave since November to remain with his family in Melbourne and has opted not to return to the Crows.
The versatile tall defender, 21, will be moved to the club's inactive list for this season and said he'd appreciated the support from Adelaide as he spent time away from the club contemplating his future.
"Unfortunately, I have lost a lot of the enjoyment and desire to improve which is required to make it at the top level," McAsey said in a statement.
"It has been an extremely difficult decision to come to, and one that I haven't taken lightly, but through discussions with close friends and family, the club and my management, I feel that it is the right decision for my long term future and well-being.
"Not everyone will understand the decision, but I'm comfortable with the path that I'm headed, and am excited by the ability to pursue other interests."
McAsey was one of Adelaide's highest-ever draft picks at pick No.6 and played 10 games in the Crows' wooden spoon season in 2020, but none in the past two years.
He re-signed with Adelaide for two years in 2021, resisting overtures from Victorian rivals.
"The welfare of our players is always our top priority and while we are naturally disappointed to see Fischer step away, we understand the reasons behind his decision and there is much more to life than football," Crows football boss Adam Kelly said in a statement.
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