Last year, McClellin was placed on injured reserve coming out of the preseason and while he was designated to return, the Patriots never activated him from the list and missed the entire 2017 season.
McClellin, 28, is a former first-round pick of the Bears back in 2012. Chicago declined his fifth-year option, which allowed him to test the open market and he eventually signed a three-year, $8.95 million contract with $3.5 million guaranteed with the Patriots in 2016.
McClellin was set to make a base salary of $2.15 million for the 2018 season.
According to OverTheCap.com, releasing McClellin will free up $2,350,000 of available cap space while creating $833,334 in dead money.
In 2016, McClellin appeared in 14 games and recorded 41 tackles, one sack and a fumble recovery.