Ballyshannon Town Councillor Rosaleen Branley had been at the centre of a party investigation after she was found not guilty of assault in a court case last year.
In a statement released today Cllr Branley said: “I am resigning from the party with effect from today, Thursday, January 19th.
“On the sad passing of my late father, Cllr. PJ Branley, I was approached by the local Sinn Féin party to carry on the work that my father had diligently carried out on behalf of the people of Ballyshannon.
“After consultations with my family and friends, I decided to let my name go forward.
“In the following election, the people of Ballyshannon came out and gave tremendous support to myself personally, and also to my family. Subsequently, I received 247 votes, and topped the poll on the first count.
“It soon became evident that a female voice in Ballyshannon was not treated to seriously and divisions appeared – in our party of equals.”