First Clear all your browsing history, cache, forms etc. by pressing Ctrl. + Shift + Del. Also remove all the save passwords from internet options security.

When you log in to Facebook uncheck the box that says "remember me" or "keep me logged in".

Now when you enter you username and password it will prompt you to save your password. Select the option not to save the password.

Hope you find this solution helpful.

Thank you for choosing Fixya