Wilkinson, 24, made six of his dozen appearances for the Pilgrims at right-back and last figured against Workington on October 22.
Jason Lee and Lee Canoville have opted to release the former Hull City trainee with Wilkinson’s first team opportunities being restricted.
Mulready, 18, has completed his month-long loan spell from Grimsby Town and returns to Blundell Park having made three starts for the Pilgrims.
Boston United would like to thank both players for their service and wish them well for the future.