S.D. Codified Laws § 47-1A-843
An officer may resign at any time by delivering notice to the corporation. A resignation is effective when the notice is delivered unless the notice specifies a later effective time. If a resignation is made effective at a later time and the board or the appointing officer accepts the future effective time, the board or the appointing officer may fill the pending vacancy before the effective time if the board or the appointing officer provides that the successor does not take office until the effective time.
An officer may be removed at any time with or without cause by the board of directors; the officer who appointed such officer, unless the bylaws or the board of directors provide otherwise; or any other officer if authorized by the bylaws or the board of directors.
In this section, the term, appointing officer, means the officer, including any successor to that officer, who appointed the officer resigning or being removed.
SDCL 47-1A-843