The four are keepers Andy Marshall and Danny Ireland, along with defender and Coventry kid Marcus Hall as well as midfielder Stephen Hughes. All of four have been offered new deals at new terms.
This means that Iain Dowie imports Arjan De Zeeuw, Ellery Cairo and Michael Hughes who have not played enough matches for a second season deal to kick in are released along with defender Colin Hawkins.
Also released are three products of the Academy in Stuart Giddings, Lee Hildreth and Liam Davis.
Reserve team joint top scorers, Wayne Andrews whose has a year left on his contract has also been allowed to find a new club as has the out of contract Donovan Simmonds who is currently on trial at Gillingham.
David McNamee has yeat to hear if he will have a deal. The likeable Scot has missed most of the season with a hamstring injury.
With Ray Ranson keen to get the squad down to 22 players, Kevin Kyle will be hoping to be offered a deal by Wolves boss Mick McCarthy whilst Gary Borrowdale may be allowed to find another club.