George Dorrington, Nick Powell, Oliver Rathbone and Victor Valdes have been released by Manchester United, the official website of the Premier League confirmed.
Multiple Champions League winning goalkeeper Victor Valdes was forced to train on his own last year after his relationship with then-manager Louis van Gaal broke down.
The 34-year-old was loaned out to Standard Liege during last winter's transfer window and is now free to join another club.
So far this summer, new manager Jose Mourinho has brought in Villarreal defender Eric Bailly for about £30million after the 22-year-old signed a four-year contract with the club.
Zlatan Ibrahimovic is expected to be the club's second summer signing after the end of his Euro 2016 campaign.