iTunes: How to unShare

I have recently found that a stranger's name was on my iTunes.

My Home Sharing is turned OFF and the name is still there.

I am connected to a wireless network on campus at my school.

Does this mean this stranger can view my iTunes?😮

Will I ever be able to get rid of this stranger's name "_____'s Library" out of my iTunes?

I have a MacBook Air and kind of still new to MacBook's😕

⚠Please Help