Sheffield United striker Jose Baxter, who was suspended twice in nine months, is one of 10 players released by the club.
In July 2015 he was suspended by the Football Association for failing an out-of-competition drugs test and then later banned by the club for an unspecified reason.
Midfielder Ryan Flynn, has also been released. Dean Hammond, who made 34 Blades appearances during his loan spell from Leicester City in the 2015-16 season, activated a clause in his contract to remain at Bramall Lane on a permanent deal but was immediately been placed on the transfer list alongside Kieron Freeman, Kieran Wallace, James Wallace, Paul Coutts, Martyn Woolford and Diego De Girolamo.
Goalkeeper George Long has been offered a new deal while Alex Baptiste, David Edgar and Conor Sammon have left the club after their loan deals expired.