The Texas Rangers released the 41-year-old slugger from his contract with Triple-A Round Rock Tuesday, opening him up to explore other options after 30 games.
"Based on our evaluation, there was not a spot on the club for Manny at this time," said Jon Daniels, the Rangers general manager.
Scouting reports found the 12-time All-Star's bat speed has slowed down significantly since he returned from a brief career playing in Taiwan earlier this season.
Ramirez was handed a 50-game suspension in 2009 after testing positive for using banned substances, and retired in 2011 rather than serve a 100-game ban for another positive test. He later agreed to take a reduced 50-game suspension and pay in the minor leagues in 2012.
Ramirez spent most of his career in Boston, where he was part of two World Series championships in 2004 and 2007.