Georgia Code Title 53. Wills, Trusts, and Administration of Estates § 53-12-40

(a) A settlor shall have no power to modify or revoke a trust in the absence of an express reservation of such power.

(b) A power to revoke shall be deemed to include a power to modify, and an unrestricted power to modify shall be deemed to include a power to revoke.

(c) Any revocation or modification of an express trust shall be in writing and signed by the settlor.