Nothing makes me feel more alone and on the periphery than Facebook. I really hate it. It makes me very uncomfortable to know that my information is being collected also. I feel it necessary to keep my account because it is so prevalent, and it seems the only way to try to stay in touch, or track down people I have lost contact with.
All that aside, you might want to look into an app called web suicide. From the appearance of it, installing it will automatically "kill" your online accounts for Facebook, Twitter and LinkedIn, and according to their website, in like under 20 minutes. Voila. I haven't used it yet, but if you do, please let me know how it went.