McIlroy will not be offering new contracts to Adam Yates, Matty Blinkhorn, Michael Howard, Diarmuid O'Carroll and Matty Bell while on-loan Peterborough striker Rene Howe will not return to Christie Park.
McIlroy said: "It's always difficult when you let players go and I would like to thank all the lads for their contribution.
"They have all played their part in our success in some way and these decisions are never taken lightly.
"We always have to look at the future though. We know where we need to strengthen next year and we will be working hard over the summer."