You'll need to check cancellation options with the transport provider. For example, if you bought a ticket on RailEasy’s website, please check what the RailEasy cancellation policy is. Tickets bought directly on the GoEuro website like those offered byRenfe, Trenitalia and Movelia may be cancelled if allowed by their terms and conditions.
To be sure of your cancellation options before you book, once you're on the page listing all of the potential transport options, click on the small (i) icon next to the price. This should then show you all the cancellation information regarding your chosen route. Additional information will also be provided during the booking process. Discounted or reduced tickets cannot be changed or cancelled - e.g. PROMO or Super Economy tickets offered by Renfe and Trenitalia respectively as well as the Reduced Fare at Movelia.