From the ticket purchase website it is not possible to cancel an accreditation or ticket already processed.

As a general rule, once the purchase is confirmed, the amount thereof will not be refunded in case of non-attendance to the event. Consequently, the non-use of the accreditation or ticket does not create any obligation of any kind for FIRA BARCELONA in relation to the return or reimbursement of the price thereof.
The cancellation and refund policy of the show is available on its ticket sales or registration page.