Mr Giri said that he has submitted his resignation to the party and it would be forwarded to the administration's principal secretary tomorrow.
He is the first to resign from the GTA as per the party's decision.
Mr Giri had stated yesterday, "We have decided to resign from the GTA." GJM supremo Bimal Gurung, who is in hiding, will also put in his papers, he said.
He alleged that the GTA has been turned into a "farce" by the West Bengal government and the GJM and the people of the hills would fight for the single agenda of a separate Gorkhaland state.
In the June 20 meeting, all the 14 influential political parties and public organisations of the hills had unanimously declared their support to the longstanding demand for a separate Gorkhaland state in north Bengal.
The GJM is spearheading the agitation for a separate state and its indefinite shutdown has paralysed hit the normal life in the hills. The GJM has been ruling GTA since 2012 and its five-year term is set to expire this year.