Former Kangaroo Chad Jones will also leave the club, along with youngster James Thomson.
Coach John Worsfold has spent the week conducting post-season interviews with all Eagles players. In a statement, the club acknowledged each player’s contribution.
Armstrong, 24, is the most experienced of the trio, having played 36 matches for West Coast, including the last six of this season.
He was picked up by the Eagles in the 2006 NAB AFL rookie draft, and had a dream start, being elevated to the senior list and playing in a premiership in his debut season.
Jones, 24, played just seven games with West Coast after being selected in the 2007 NAB AFL rookie draft. He was delisted by the Kangaroos in 2006, having played six games.
Thomson, 20, was taken with selection 80 in the 2006 National Draft, but did not play a senior game.
