Brewer's bonds may be terminated as to liability for future removals or receipts (a) pursuant to application of the surety as provided in Sec. 25.103, (b) on approval of a superseding bond, or (c) on notification by the principal that the business has been discontinued. On termination of the surety's liability under a bond, the appropriate TTB officer will notify the principal and sureties. (31 U.S.C. 9301, 9303)