Ind. Code § 8-3-17-8

Sec. 8. When a company no longer requires the services of a policeman, it shall file a notice to that effect, under its corporate seal, with the clerk of the circuit court of the county where the commission of that policeman is recorded, which shall be noted by the clerk of the circuit court upon the margin of the record where the commission is recorded. The company shall also file notice with the Indiana department of transportation. Thereupon, the powers of that policeman terminate.