Releasing Sherman is one of just a handful of moves the team has made or appears on the verge of making as it clears cap space on the eve of free agency.
Seattle is also expected to soon release cornerback Jeremy Lane, which would save $4.75 million against the cap.
Combined with the trade of Michael Bennett, which saves $2.2 million, and what also could be the release of Avril (which would save about $6.4 million with the injury guarantee factored in) Seattle would be creating roughly $24 million additional in cap room.
Seattle is listed as having roughly $13 million as of Thursday morning but could have about $37 million with all of those moves.
What the Seahawks plan to do with the money is unclear.
Seattle has had veteran linebacker Brian Cushing and running back Jonathan Stewart in for visits the past two days. But both would almost certainly be one-year contracts for at or close to the veteran minimum if they sign. There was no immediate word on if either will.
The Seahawks could be saving up to try to re-sign defensive lineman Sheldon Richardson, who the team declined to place a franchise tag on at $13.9 million this week, meaning he can become a free agent Wednesday.
But in what is a weak crop of free-agent defensive linemen the general thought is that Richardson wants to hit the open market before committing anywhere.
Seattle also could be creating space to extend the contract of left tackle Duane Brown, who was acquired in October and whose deal runs out following the 2018 season. Brown, 32, is due $9.75 million in 2018.
And Seattle also could be creating some flexibility to extend the contract of free safety Earl Thomas. The Seahawks appear likely to keep Thomas rather than trade him but know they'll have to give him a contract that could approach $14 million a year. He is entering the final year of a contract that pays him $10 million a season.