Ga. Code § 36-36-22
Authority is granted to the governing bodies of the several municipal corporations of this state to deannex an area or areas of the existing corporate limits thereof, in accordance with the procedures provided in this article and in Article 1 of this chapter, upon the written and signed applications of all of the owners of all of the land, except the owners of any public street, road, highway, or right of way, proposed to be deannexed, containing a complete description of the lands to be deannexed and the adoption of a resolution by the governing authority of the county in which such property is located consenting to such deannexation. Lands to be deannexed at any one time shall be treated as one body, regardless of the number of owners, and all parts shall be considered as adjoining the limits of the municipal corporation when any one part of the entire body abuts such limits. When such application is acted upon by the municipal authorities and the land is, by ordinance, deannexed from the municipal corporation, an identification of the property so deannexed shall be filed with the Department of Community Affairs and with the governing authority of the county in which the property is located in accordance with Code Section 36-36-3. When so deannexed, such lands shall cease to constitute a part of the lands within the corporate limits of the municipal corporation as completely and fully as if the limits had been marked and defined by local Act of the General Assembly.
OCGA § 36-36-22