Releasing a mechanics lien is an easy process. Generally, all a lien claimant must do is fill out a simple lien release form and either file the document themselves, or provide that to the owner or other interested parties.
Levelset actually has a free, downloadable lien release template that might be useful, here: Tennessee Mechanics Lien Release Form. Additionally, you can find your county recorder's contact and filing information here: Tennessee County Recorders.
Of course, note that there are services out there - like Levelset, other online companies, and law firms - who can assist with that as well. To use Levelset, you can begin the process here: Order a Document. If you'd like to find an attorney who could help, here's a good place to start: Top Tennessee Construction Lawyers.
When the customer pays in full in TN, if there is a lien recorded in the Register of Deeds' Office, you can file a Release of Lien in the same office and reference the instrument number for the lien.