The Lions waived Quin after six seasons with the franchise. The team also released wide receiver Bruce Ellington and linebacker Nicholas Grigsby.
"We thank Glover for his countless contributions to the Detroit Lions during his six seasons with our team," Lions executive vice president and general manager Bob Quinn said. "Since joining the organization in 2013, Glover exemplified everything it means to be a true professional in this league -- as both a competitor on the field and a leading voice in the community.
"Coach [Matt] Patricia and I have the utmost respect for him as a man and player, and we wish him nothing but the very best in the future."
The Houston Texans selected Quin in the fourth round of the 2009 NFL Draft. After four seasons with Houston, he became an unrestricted free agent following the 2012 season.
Quin signed a five-year, $23.5 million contract with the Lions on March 13, 2013. Detroit gave him a two-year extension worth $13 million, with $9.5 million guaranteed, in 2017.
The Lions will save $6.25 million on the salary cap by releasing Quin. The veteran safety posted a farewell message on social media.
The 33-year-old safety started all 96 regular-season contests in his six-year stint with the Lions. He had 74 total tackles, one sack and three passes defensed last season.
In 10 NFL seasons, Quin has recorded 737 total tackles, 24 interceptions, four sacks, 85 passes defensed and two defensive touchdowns.
Ellington played in four games for Detroit last season and tallied 23 catches for 132 yards. Grigsby split time between the New England Patriots and Lions in 2018. He saw action in 12 games and had 10 tackles.