Hello Maittoogou89
Welcome to the SBB Community.
You are talking about the Swiss Travel Pass.
You can get a full refund, provided you have purchased it from SBB as a registered user. If you purchased it as a guest, there is a CHF 10 refund request processing fee per request.
More information can be found here:
https://www.sbb.ch/en/help-and-contact/refunds-compensation/refunds-compensation/ticket-refunds.html
Here is the refund request form if you have purchased the STP as a guest:
https://www.sbb.ch/en/help-and-contact/refunds-compensation/refunds-compensation/refund-form.html
If you purchased the Swiss Travel Pass from another reseller, please refer to them for a refund.
In my opinion, it makes little sense to purchase a Swiss Travel Pass that far in advance. The cost is not higher when you purchase it right before travel; it is the opposite, you can save the cancellation fee.
Kind regards,
Roland