Hello student there's no option left now as you've make the mistake yourself by applying for b.ftech instead of B.design.

As this year exams has already passed you need to appear in next year nift entrance examination and make sure you won't make any mistake.

Eligibility for bachelor design :-

Candidates must have passed class 12 (or appearing) from any discipline from a recognized board.

Feel free to comment if you have any doubt

Good luck