He was due to have $4.5 million of his $8 million salary for 2018 become guaranteed on Sunday.
Hankins will visit the Washington Redskins, sources told ESPN's John Keim.
Hankins had 44 tackles and two sacks while starting all 15 games that he appeared in during his lone season with the Colts.
The Colts, who are transitioning to a 4-3 defense under new coordinator Matt Eberflus, have Al Woods, Henry Anderson, Grover Stewart and Hassan Ridgeway playing on the interior part of the line on the roster. They also signed versatile lineman Denico Autry on March 15.
Hankins, who turns 26 at the end of March, signed with the Colts after creating one of the strongest interior lines with the New York Giants during the 2016 season, when he finished with 43 tackles, 3 sacks, 8 tackles for loss and 10 quarterback hits.
Hankins was a second-round pick by the Giants in the 2013 NFL draft. He has been a four-year starter, appearing in 67 games and recording 184 tackles along with 12 sacks and 3 forced fumbles.