Thomas was expendable for the Cardinals after they traded for Matt Barkley a few days ago.
Thomas, 24, still has another three years remaining on his four-year, $2,652,092 rookie contract, which includes base salaries of $510,000 (2015), $600,000 (2016), and $690,000 (2017).
According to OverTheCap.com, releasing Thomas would free up $293,954 in available cap space while creating $324,069 in dead money.
Last year, Thomas appeared in two games for the Cardinals, even though they lost Carson Palmer and Stanton for the season. He threw for 81 yards and a touchdown, but completed just a single pass attempt.