I've installed the Internationalization module in order to make a multilingual site, I've set italian as default language, but there's a problem, the front page is always in english. I've checked the base URL and I've noticed that there's a language prefix, is it possible remove?
I think you're mixing a few things here, and I also think that the comment in the question (which should actually have been posted as an answer ...), is only like a partial fix or workaround. What, IMHO; the real issue seems to be here, is that the URL of the homepage has not been defined as a "multilingual" variable, as further explained below.
The relative URL to display as the front page is specified within admin/config/system/site-information . If you want to be able to specify a value for it that is different for each of the site's languages, make sure you have made it a "multilingual" variable (it should say "This is a multilingual variable.") in the description of that variable on that page.
For more details about how to get this done, refer to my answer to How to make content translation available for front page?.