If you want to deactivate your facebook account, for reasons best known to you, you can easily get it done by following some few steps.
Login To Your Facebook Account.
Click on the "Account" link located by the top-right corner of your screen.
Then, click on "Account Settings" as indicated in the picture below:
Thereafter, you will see a new page. Scroll down till you see "Deactivate account" as in the picture below:
I hope it works for you.