Tenn. Code § 33-5-303
In the case of a person admitted under § 33-5-301, a parent or legal guardian of a child with intellectual or development disability on behalf of the child, a conservator of a person with intellectual or development disability on behalf of the person, or a person with intellectual or development disability who was admitted on the person's own application and does not lack capacity under § 33-3-218 may request discharge from a developmental center at any time by filing a request with the chief officer or director of a center or the appointed designee. If the person cannot file a written request, anyone acting on the person's behalf may file the request with the person's consent. The chief officer or director of a center or the appointed designee shall discharge the person with intellectual or development disability within twelve (12) hours after receipt of the request or at the time stated in the request, whichever is later.
T.C.A. § 33-5-303