No will or codicil, or any part thereof, shall be revoked, unless under the preceding section, or by a subsequent will or codicil, or by some writing declaring an intention to revoke the same, and executed in the manner in which a will is required to be executed, or by the testator, or some person in his presence and by his direction, cutting, tearing, burning, obliterating, canceling or destroying the same, or the signature thereto, with the intent to revoke.