Dear,
The last date of correcting the application form has already gone. You cannot make any changes online.Since you have done the slot booking the admit card would have been formed and emailed to you.So making a correction at this point of time is quite difficult.But you can try by contacting to the authorities through the below mentioned details:
VIT University,
Vellore – 632014,
Tamil Nadu

Helpline number:
0416-2202125
0416-3305555
You can call from 9 am to 6 pm.
I hope this helps.