Hello Rohith,

During counseling if you allotted a seat then you have to report at any nearest NITs /IITs for conformation of seat . At this stage if you unable to provide  valid EWS certificate then you will automatically change to General category for further round, and college would be alloted as per open category.

For more information you can visit here - https://engineering.careers360.com/articles/josaa-counselling

Hope it Helps :)

Best of Luck .