Byron, a 19-year-old centre back, didn't make it to the first team in a competitive game. His only taste of professional football to date has been three appearances on loan for Notts County this season.
Midfielder Fry, 21, has long been involved in the first team squad, but since making his debut in the LDV Vans Trophy in 2002, has only made a further 4 appearances.
Matthews was tipped as a bright prospect but failed to make the breakthrough.
Wiseman, 21, progressed the furthest of the four, making 19 appearances for City at right-back. He gained extra first team experience with loan spells at Rotherham and Darlington this season, but didn't make it into Brown's plans.
Meanwhile, 19-year-old goalkeeper Curtis Aspden has been offered a one-year deal.