Tenn. Code Ann. § 33-6-207

If the chief officer receives a request for discharge under § 33-6-206 and does not admit the service recipient under chapter 6, part 4 of this title, the chief officer shall release the service recipient, if a child, within twenty-four (24) hours and, if an adult, within twelve (12) hours after receipt of the request or at the time stated in the request, whichever is later.