Hello Pankaj!

You can not cancel the registration if the modification limit is over.

however,if you want to make any changes or mordify some details what you can try is open a new form and fill it up with another email id or if it doesn't work make some minor changes either your father's name, DOB or your name (father's name seems more safe to me) that has worked for people. keep in mind that you can not cancel the registration once submitted they do not allow it, so when you are filling the forms you need to be extra careful, recheck what you have typed at least twice to avoid further problems like this.

All the best !

Hope this was helpful!