McClain still had two years left on the $40 million, five-year rookie contract he signed in 2010. That deal included $23 million in guarantees.
McClain is the third player drafted in the top 10 by late owner Al Davis to be let go so far this offseason by second-year general manager Reggie McKenzie. Defensive back Michael Huff (seventh pick in 2006) and receiver Darrius Heyward-Bey (seventh pick in '09) were cut last month.
Oakland has only two of its own first-round picks on the roster in running back Darren McFadden and kicker Sebastian Janikowski as McKenzie overhauls the roster. There are only 15 players left who were part of the organization at the end of the 2011 season.