20 CFR §217.26

1. (a)Before an annuity is awarded. The application may be cancelled if—
   1. (1)The applicant files a written request with the Board at a place described in § 217.15 asking that the application be cancelled or stating that he or she wants to withdraw the application;
   2. (2)The claimant is alive on the date the written request is filed or the claimant is deceased and the rights of no person other than the person requesting the cancellation will be adversely affected; and
   3. (3)The applicant files the written request on or before the date the annuity is awarded.
2. (b)After an annuity is awarded. The application may be cancelled if—
   1. (1)The conditions in paragraph (a)(1) and (2) of this section are met;
   2. (2)Any other person who would lose benefits because of the cancellation consents to the cancellation in writing; and
   3. (3)All annuity payments already made based on the application being cancelled are repaid or will be recovered.