SDCL § 34-12H-9: Revocation of MOST.

A patient with decision-making capacity may revoke a MOST at any time by:

(1) Destroying or defacing the MOST with the intent to revoke;

(2) A written revocation of the MOST, signed and dated by the patient; or

(3) An oral expression of the intent to revoke the MOST, in the presence of a witness eighteen years of age or older who signs and dates in writing, confirming that the expression of intent was made.

An authorized representative may not revoke a MOST unless the MOST was executed by the authorized representative. The authorized representative shall make the revocation in writing.

A revocation is effective upon communication to the health care provider. A health care provider who is informed of a revocation shall record the date and time of the notification of revocation in the patient's medical record.