Keep in mind that it will never really go away. You can dis-activate it but go back to it if you change your mind and everything will be as you leave it. All you have to do is log back on with your old password and email/#.
So basically it's equal to simply never logging on again. Stupid. I know!
If you truely want to "delete" it. Then unfriend everyone. Delete everything. (Pictures, posts, apps, likes, etc). And you have an empty facebook page. You can be drastic and change the email or phone # with a fake one.
[email protected] or whatever. Most people don't think it's worth it to go through all the trouble... It's your choice.
To dis-activate go to settings then security. Option will be on the bottom.