How to Deactivate Facebook Account
1. Log in to Facebook and On settings top right corner choose Settings.
2. Now choose Security Tab, look for Deactivate your account, at bottom, Or else click this url to go directly
3. Now Choose Deactivate account, see direct link https://www.facebook.com/deactivate.php
4. A page will open asking you to Reason for leaving just fill it and Confirm.
PS: You can also deactivate your Facebook account temporarily for some point for time, look for options in the window page.