Nairobi County cabinet executive in charge of Education Janet Ouko resigned on Monday afternoon.
She was speaking at City Hall when she stated that she was giving up her job in order to pursue other interests.
During her resignation, she also cited other challenges including a small number of schools against a huge population.
The CEC stated that she had served Nairobi Governor Mike Sonko with her resignation letter and was awaiting his response.
She has now become the second member of Sonko's Cabinet to resign after Deputy Governor Polycarp Igathe left in January 2018.
Prior to joining the Nairobi County government, Ouko was an activist championing education reforms.
She later unsuccessfully sought the Jubilee ticket to contest Nairobi Women Rep's position.
Sonko had also included her in her shortlist of potential running mates before he finally settled on Igathe.
Janet has been at the forefront of demanding for education reform in Kenya since 2005 and has seen the sector transform through the constitution-making process to acknowledge education as a social-economic right and to recognise the role of citizen participation in processes.
The former activist has led Kenyan education civil society in supporting the Ministry of Education to realign itself to the Constitution of Kenya and Vision 2030, which is Kenya’s medium-term development blueprint.
She had also been appointed by the former Governor of Nairobi Evans Kidero to serve as Vice Chair of the task force to improve the performance of public schools in Nairobi County.