Hello Ckepoojue85
No, this is not possible, you would have to cancel the ticket and repurchase. To provide accurate advice, it all depends on who has issued the ticket, and the ticket type itself.
If the ticket was purchased from SBB, please call SBB or see a station travel office. An online cancellation is not possible.
+41 51 225 78 56 (24/7, waiting times may occur).
Kind regards,
Roland