The 23-year-old battled an assortment of conditions throughout his career. An infection before the start of 2013 training camp ultimately landed him on season-ending injured reserve. He never played a game with the team.
Orton, 31, is considering retirement and skipped the team's entire offseason program. His release adds $1.1275 million to the Cowboys' salary cap this season and $2.255 million in 2015.
While Orton has not made any public comments this offseason, if he retired under contract he would be required to repay $3 million from his signing bonus.
The Buffalo Bills signed free agent linebacker Stevenson Sylvester, the team announced. Sylvester worked out for the team Wednesday morning and was signed in the afternoon.
Sylvester (6-foot-2, 231 pounds) played the last four seasons for the Pittsburgh Steelers mainly on special teams. The former fifth-round pick in 2010 has appeared in 50 games in his NFL career and has lined up at both inside and outside linebacker.
To make room for Sylvester on the roster, the Bills released tight end Mike Caussin, who battled injuries through much of his time with the Bills.
(Editing by Gene Cherry)