S.D. Codified Laws § 2-1-18.1
An individual who has signed a petition to initiate a constitutional amendment or measure, or to refer a law, may submit a written notification to the secretary of state stating that the individual's name be withdrawn from the petition. A signature may be withdrawn as provided in § 2-1-18.2.
The written notification must include:
The individual's signature on the written statement must be witnessed and notarized by a notary public commissioned in South Dakota or other officer authorized to administer oaths pursuant to § 18-3-1. For a written notification to withdraw a signature to be valid under this section, an individual must submit the written notification to the secretary of state at any time before the petition from which the individual is submitting a written notification for withdrawal under this section and § 2-1-18.2 is filed and certified for placement on the next general election ballot under § 2-1-17.
The written notification may be delivered by hand, or United States registered mail to the secretary of state.
SDCL 2-1-18.1