It said the party cannot accept anyone else other than its founder, the late M G Ramachandran, and the late chief minister J Jayalalithaa as general secretary.
A meeting of the general council, the apex decision making body of the party, and the executive committee passed a resolution to cancel Sasikala's appointment, sources said.
The meeting also resolved to amend the party's by-laws, indicating that there would be no general secretary in the future.
Party affairs would now be managed by a steering committee, as announced during the merger of the factions led by Chief Minister K Palaniswami and his Deputy O Panneerselvam on August 21.
It was attended by, among others, Palaniswami and Panneerselvam and presided over by party presidium chairman E Madusudhanan.