Sections 29A-2-507, 29A-2-508 - Revocation by writing or by act. Revocation by change of circumstances - South Dakota Statutes

29A-2-507. Revocation by writing or by act. (a) A will or any part thereof is revoked:
(1) By executing a subsequent will that revokes the previous will or part expressly or by inconsistency; or
(2) By performing a revocatory act on the will, if the testator performed the act with the intent and for the purpose of revoking the will or part or if another individual performed the act in the testator's conscious presence and by the testator's direction. For purposes of this paragraph, "revocatory act on the will" includes burning, tearing, canceling, obliterating, or destroying the will or any part of it, whether or not the revocatory act touched any of the words on the will.
(b) If a subsequent will does not expressly revoke a previous will, the execution of the subsequent will wholly revokes the previous will by inconsistency if the testator intended the subsequent will to replace rather than supplement the previous will.
(c) The testator is presumed to have intended a subsequent will to replace rather than supplement a previous will if the subsequent will makes a complete disposition of the testator's estate. If this presumption arises and is not rebutted by clear and convincing evidence, the previous will is revoked; only the subsequent will is operative on the testator's death.
(d) The testator is presumed to have intended a subsequent will to supplement rather than replace a previous will if the subsequent will does not make a complete disposition of the testator's estate. If this presumption arises and is not rebutted by clear and convincing evidence, the subsequent will revokes the previous will only to the extent the subsequent will is inconsistent with the previous will; each will is fully operative on the testator's death to the extent they are not inconsistent.

Source: SL 1995, ch 167, § 2-507.