Both players will now become unrestricted free agents.
Athanasiou, 26, registered 11 goals and 15 assists for 26 points through 55 games in 2019-20. Most of that was spent in Detroit before landing in Edmonton at the trade deadline. He carried a $3-million cap hit in each of the past two seasons.
Benning, 26, came in at $1.9 million in each of the past two campaigns. He provided some solid blue line depth for Edmonton through much of the season and should suit up in a similar role on an affordable deal in free agency.