Hello,

Unfortunately it is not possible to change your subject from standard to basic as your registration has already happened for boards along with your admit card printings and every board allows subject change only till July as they have to start registering the students for the boards.

Hence, it is not possible for you get your subject changed so I will recommend you to work a little harder as you still have a month left for your board examinations.

Hope this helps you,

All the best