how deactivate Vodafone data options online?
 

I want do deactivte my Data Option Internet go on the internet site of vodafone.it
How can I do this? I only find the possibility to renewal the option.
Please help me.

Uhm, usually you have to call the 42070 (or 190, the customer service), free if you are in Italy.
On the www.190.it you should be able to deactivate any option clicking on the "Attiva Servizi e Promozioni" menu, where you should find a "Disattiva" option besides your data option. But I don't own a Vodafone prepaid so I cannot check it for you, sorry.
Otherwise let the sim die and you will get a new one once you come back to Italy.