The lessee under any oil and gas lease granted by the state may at the termination of any rental year, by giving to the department 30 days' previous notice in writing, surrender and relinquish the lease to the state in whole or as to any legal subdivision of the lands covered thereby and be discharged from any obligation not yet accrued as to lands so surrendered and relinquished without prejudice to the continuance of the lease as to lands not surrendered or relinquished.
§ 77-3-439, MCA