When you are the only person who uses a particular computer, staying logged in to various websites or allowing them to remember your username and password can help save time. When other people use the computer, however, this feature can lead to a severe lack of privacy. Instead of risking having another person read your private Facebook messages or make updates to your account, stop Facebook from remembering your username and password.
Direct your browser to your Facebook account. Because Facebook remembers your username and password, you are not asked to sign in at this point.
Click the "Account" option in the upper right corner of Facebook, and then click "Log Out." This signs you out and takes you to Facebook's sign-in page.
Type the email address and password associated with your Facebook account into the appropriate fields on this page. Click the "Keep Me Logged In" box to remove the check, and then click "Log In." This stops Facebook from remembering your information and logging you in automatically.
If Facebook continues to remember your username and password, you may need to modify your browser's settings.