Wanna commit social suicide but don't really want to deactivate your facebook? DO THIS!
1) Go to notepad
2) Type any random word and number combination a with your eyes closed. Don't look at your new combination for risk of you remembering it.
4) Go to your email and fb page for change password
5) Enter your current password
6) Ctrl+v to both field of new password and confirm your new password. Click SAVE.
7) Go to notepad
8) Type your old password
There you go. You won't be able log in to your fb and retrieve it in your facebook email the password anymore because you don't know what it is. Do not do this unless you are absolutely certain you won't have any more need for your facebook and your email. I recommend you change your primary email to something you don't usually use before your abandon your email because sometimes this is very important not to burn bridges with some people who might want to contact you for business and personal concerns.