how can a student take admission in nit or other equivalent colleges if that student has already taken admission in some local college prior to jee result ,as the local college asks to deposit the necessary doc which is also required during jee councelling and admission?

Hello,
You need to immediately inform the authorities about you cancellation of your admission. You will get a refund of the fees if you deposited if any. They will cut a portion of the fees as cancellation fees. Also they will then return all the documents which you have deposited. Keep in mind to check that they have returned all the documents or you might face problems in the future.

Hope it helps