When you sign in to Facebook, you have the option of telling the site to remember you. If you select this option, you do not need to sign in to Facebook when you come back. Instead, it signs you in automatically. While this can certainly save time, it can also be frustrating if you do not actually wish to be signed into that account. Facebook, unlike some other sites, does not have an obvious "Sign out" button at the top of each page. Once you know where to look, however, you can sign out easily from any Facebook page.
Look in the upper right corner of any Facebook page. You should see three options: "(your name)," "Home" and an inverted triangle symbol.
Click the triangular symbol to open another set of options. "Helps Center," "Account Settings," "Privacy Settings" and "Log Out" are displayed vertically.
Click "Log Out," located at the very bottom of this list of options. Doing so signs you out of Facebook.