You should only be able to do that from wherever you created it, and it's unlikely to be the Italian ebay.
However, try here http://cgi1.ebay.it/ws/eBayISAPI.dll?CloseAccount you will need to select a reason
Please be aware you won't be able to unless you never tried to sell or buy anything, ebay will stop you from doing so if you have any pending issues such as non-payments
And in principle it's unlikely you'll be able to close it before 30 days from opening, why did you open one to start with?
