Glenn was removed from the concussion protocol on Wednesday. However, he argued with a member of the Bengals' coaching staff that day because the veteran feels the team rushed him back from the injury, with one onlooker believing the confrontation was close to turning physical.
Glenn reportedly told head coach Zac Taylor to release him.
Cincinnati and Glenn have clashed over "the concussion, its symptoms, whether he's able to return, the need for second opinions, and how the player feels," according to Florio.
Because of those issues, the Bengals, at some point this season, fined Glenn $200,000 for conduct detrimental to the team.