43 C.F.R. § 3108.10
The lessee(s) may relinquish the lease or any legal subdivision of the lease at any time. The lessee(s) must file a written relinquishment with the BLM State Office with jurisdiction over the lease. All lessees holding record title interests in the lease must sign the relinquishment. A relinquishment takes effect on the date the lessee filed it with the BLM. However, the lessee(s) and the party that issued the bond will continue to be obligated to: