Releasing a mechanics lien is relatively easy, just like filing one. Essentially, all it requires is filling out a mechanics lien release form that indicates you were paid in full, then having that document filed with the county recorder's office to indicate the lien was paid.
You can find a free, downloadable template for a Nevada mechanics lien release here: Nevada Mechanics Lien Release Form. And, you can get the contact info for the appropriate county recorder here: Nevada County Recorders.
Of course, keep in mind that there are services - like Levelset - which can assist in filing a mechanics lien release and make that process a breeze. You can get that process started here, if you'd like: Levelset Document Navigator.