Tyagi...
Please find the link below to surrender the duplicate/unwanted PAN...
You should keep one PAN to surrender other PAN, i mean you can can not surrender the only PAN.
If the above link is not working, copy and paste below line to your browser address bar (where you types www.caclubindia.com)
>>www.sparsh*tax.net/pan/newPAN.asp
(Tip> type 'i' in place of '*' given above)
**DM