Hi JUN
It’s sad to hear you are leaving our country.
The cancellation is possible through your SwissPass account.
If you feel overwhelmed by doing so, please either see an SBB ticket desk, for example at Bern station, or call the SBB Contact Center.
https://sbb-tickets.cc/en/help-and-contact.html
On this platform, we are unable to help you with the cancellation of your travel cards and/or half fare cards.
All the best.
Best regards,
Roland