Tennessee Code Title 66. Property § 66-25-101

(a) When a debt secured by a mortgage, deed of trust, or by lien retained in a deed of conveyance of land or bill of sale, or other instrument, has been fully paid or satisfied, the mortgagee, transferee, or assignee of the mortgagee or the legal holder of the debt secured by deed of trust or lien, who has received payment or satisfaction of the debt, must satisfy the record by a formal deed of release.

(b) In any county having a population of not less than thirty-two thousand six hundred (32,600) nor more than thirty-two thousand seven hundred (32,700), according to the 1980 federal census or any subsequent federal census the record may be satisfied by entry on the margin of the record of the mortgage, deed of trust, deed or other instrument.