Hiii aspirant..

The Indian Certificate of Secondary Education (ICSE) is an examination conducted by the Council for the Indian School Certificate Examination, a private board of school education in India. It has been designed to provide an examination in a course of general education, in accordance with the recommendations of the New Education Policy 1986 (India), through the medium of English.

Source- Google. 

Thus I want to let you know that ICSE is neither State Board nor Central Board but it is a private board.

Hope it helps. 

Best of luck.