Evans's 35 goals helped fire the Blades to the brink of automatic promotion, but he missed the last three games of the regular season after being found guilty of rape and sentenced to serve five years in prison.
The Blades paid £3 million to Manchester City for Evans in the summer of 2009 and the 23-year-old, who signed a three-year contract, made 113 appearances, scoring a total of 48 goals.
Goalkeeper Simonsen, 33, made a series of outstanding saves in Saturday's penalty shoot-out defeat to Huddersfield before missing the decisive spot-kick in their agonising 8-7 defeat.
The former Everton and Stoke goalkeeper, a free signing after an initial loan spell in July 2010, made 103 starts for the Blades and two substitute appearances.
Fellow first-team players James Beattie, Johnny Ertl and Andy Taylor, who hit a post in the shoot-out, have also been released along with reserve-team players Jack Adams, Connor Brown, Seamus Conneely, Corey Gregory, Shane Murray and Marc Warren, while new deals have been offered to midfield pair Kevin McDonald and Lee Williamson plus striker Chris Porter.