Gobnait Ní Chrualaoí submitted a letter of resignation to the Chair of the Board of Trustees on Tuesday.
It follows the resignation of six of the seven trustees on the 8th of December.
In the two-page letter, Gobnait Ní Chrualaoí said that achieving CoAction's vision, mission and objectives continues to be an ever-increasing challenge and said there are a number of complex and inter-related factors that contribute to this including: staff recruitment and retention, and the growing pay gap and poorer terms and conditions of CoAction staff compared to Section 38 and HSE staff.
The former CEO also cited what she described as the "ongoing undermining and challenging of the CEO's integrity and members of the Senior Management Team by a small cohort of members who are not accountable for the day to day running of the organisation."
Parents of children attending the disability service in Bantry staged a number of protests outside the purpose built centre to oppose plans to convert it into a residential unit for adults.
Around 180 children attend the centre in the town.
