Thats simply impossible-with a little thought you should have thought of same. You have to send them back to office in UTrecht before start date.
Just google : and find the page on whattodo in these cases. it would also have been much more easy for you if you had simply went to OeBB and bought it there-and asked same time about to do the RES-an could have waited for buying-or not-till just before departure
If you log into your Interrail account and look at the Order Overview, there will be a section on refunds and exchanges where you can read everything about how to make your return.
“... You have to send them back to office in UTrecht before start date.”
“... where you can read everything about how to make your return.
I read the instructions but still do not know if I have to desactivate the passes BEFORE sending them back. And if so, how to desactivate them. That was my question and I still don’t have an answer. Sorry.
The information is here:
https://www.interrail.eu/en/interrail-passes/ordering-info/refund-exchange-policy
"Paper Pass with a predefined start date
If you selected a start date during the order process, you must submit your refund request before the first day of validity of the paper Pass. However, in case you decided not to use your Pass and asked a railway official in Europe to certify your Pass as ‘NOT USED’ before the first day of validity, the refund request can be submitted no later than six months from the last day of validity of the paper Pass"