Valverde, 35, made 20 relief appearances with the Tigers this year and struggled to a 5.59 earned run average. He lost his only decision.
Detroit chose not to sign Valverde to a major league contract during the offseason, but he eventually agreed to a minor league deal. He made his season debut April 24.
Valverde will now go on waivers, and if he clears them he would likely be sent to Detroit's Class AAA team in Toledo.
He has a 26-32 career record in 605 relief appearances. Valverde has never started a major league game.