Cancellation of pan

Dear All please answer the query ASAP.

My aunty is holding two PAN(s) by default.She is filing her ITR with the PAN no. in which her sur name is incorrect because she was unaware of the fact that she is holding two PANs and the worst thing is that the PAN card in which her sur name is incorrect  has not been with her since past few years.Now we want to cancel this PAN but we don't know the procedure.Please tell me the procedure to cancel the wrong PAN keeping in mind that my aunty is not holding this PAN card physically.

Thanks