Yes you can change your CBSE Board to JKBOSE in class 12 but you will have to give a proper reason to CBSE for changing the board then only CBSE permits you to change the board.

Further you can contact the school you wish to join and they will provide you the information regarding changing board, documents required, etc.

So if you want to change the board then mention your reason and submit it to CBSE requesting to change your board