Pan card question

sir,

one of my client have 2 PAN . 1st PAN ( still active)  is not linked with addhar but linked with all bank accounts. as accidentally ( lack of awareness) he taken 2nd PAN through E- PAN based on addhar & accordingly new pan linked with addhar. now client want to surrender new PAN, de-attach addhar and attach with old PAN. There is no return submitted too for both PAN since last 3 years.  pls help us to get procedure so that old PAN can be attached with addhar. considering the 31st Dec, can we file return on old PAN & verify it other than addhar option