Hi there,

You have not mentioned the name of the entrance exam for which you have filled the form, but generally you are not allowed to get reservation if you have filled your category different in the form. To get EWS reservation you can edit the details in the form you have filled provided it is allowed or you can fill another fresh form for the same exam and then fill you category correctly.
you can apply for EWS certificate but if you have filled your category wrong in the entrance form then you will not be able to avail the benefit of reservation.