10 December 2016
Surrender one among the two by using the form available in https://www.tin-nsdl.com/download/pan/PAN-CR-Form_NSDL%20e-Gov_01.06.16.pdf
10 December 2016
There are both, online and offline process available for surrender of PAN. you can follow one of them . You can surrender online and still file letter with AO. If you are filing with AO, do not forget to obtain an acknowledgement.