Itunes auto-sharing

So, I was remoting into a computer at work to allow our sales guy access to Itunes so he could upload photos from an Iphone.  He opens the Itunes and I see all the songs I have stored on my own workstation.  How do I stop this type of auto-sharing?  It seems like Itunes went through my network, found available music, and gave this sales guy the ability to upload them into his own laptop!  What the heck is that? Solution: Itunes auto-sharing try the following solution: http://www.ehow.com/how_4512701_turn-itunes-library-sharing-off.html