McClain was conditionally reinstated to the NFL before the start of the season and was later released by the Cowboys in early September.
Reports from this past summer said that McClain was looking to resume his NFL career, but he ultimately found no interest.
McClain, 30, is a former first-round pick of the Raiders back in 2010. He spent three years in Oakland before taking a year off and later signing with the Ravens.
Baltimore traded McClain to the Cowboys in 2014, and Dallas elected to bring him back on a one-year, $5 million contract back in 2016. He was later placed on the reserve/did-not-report list.
McClain was then suspended indefinitely without pay for violating the NFL Policy and Program for Substances of Abuse.
For his career, McClain has recorded 405 tackles, 9.5 sacks, four interceptions, two forced fumbles, a defensive touchdown and 25 pass defenses over the course five seasons and 65 games played.