If you need to cancel or surrender your existing PAN card, you must visit your local Income Tax Assessing Officer. You'll need to submit a formal request letter detailing your intention to surrender the PAN. Be prepared to specify the reason for your surrender when you make the request.
If you wish to cancel/ surrender your PAN (which you are currently using), then you need to visit your local Income Tax Assessing Officer with a request letter to cancel/ surrender your PAN.