Hey Arjun !
Well, this is quite a common mistake that students perform at the time of UG form filling.
In order to rectify the mistake, the authority generally selects a subsequent date after the form filling wherein the students can check their form fillup and make any required corrections.
Same can be the issue to solve yours too if at all the authority provides you a future date.
Other option can be to directly contact with the authority, with Mail or Telephonic conversation.
The office personnel would help you out in the matter as the issue requires different mode of action in different application forms.

Good Luck !
Try to contact at the earliest.