The Northern Ireland winger has fallen out of favour this season, undertaking a loan spell at Notts County during March, and he has long been tipped for a return to former club Hibernian.
John Akinde, Patrick Hoban and Jimmy Keohane are the other players that have been told their contracts will not be renewed this summer.
Meanwhile, David James is entitled to a new deal after satisfying a clause in his contract relating to appearances this season.
Fellow goalkeeper Dean Gerken has signed a new two-year deal and third-choice stopper Stephen Henderson, who shone during a loan spell at Yeovil this season, has been offered a two-year contract.
Young defender Joe Edwards, who made his full debut against Hull on Saturday, has signed a one-year deal with fellow academy product Marlon Jackson set to do likewise shortly.
Source: PA
Source: PA