To change your name in your ICSE Class 10 marksheet, you have to apply through your school where you were registered; first, you need valid supporting documents such as a gazette notification, affidavit for name change, and updated ID proof, then submit a formal application to your school, which will forward it to the board for correction/rectification; if the change is minor (like spelling correction), it may be easier, but for a complete name change, the board strictly requires legal proof and may allow it only within a certain time limit after result declaration.

You can check the detailed process for the Ke ndriya Vidyalaya Admission and online registration here. Know the step-wise Kendriya Vidyalaya admission procedure for classes 1 to 12 here.