remove site name in adminbar for contributors roles

Hello, im new in using wordpress. For now on, I know how to hide admin bar for some users,I make my dashboard accesible only for admin,editor and author only. But i want to remove some links in admin bar. I want to remove site name links from the adminbar. so only the admin,editors and author can view it. because it is for admin, editor and author only. sorry for my wrong english grammar thanks.