How to Edit Your Facebook/Twitter History
"Quitting is harder than you might think," reports Molly Wood, as she explains that finding the link to quit Facebook is rather difficult, and even then, the actual deletion takes up to 90 days. In this video, Wood walks us through some easy ways to clean up old Facebook and Twitter posts, change privacy settings, download all posts (a very handy feature even if you don't want to delete anything), and leave the services. If you're rethinking your relationship to social media, here's a good starting point:
There's more in her article for the New York Times. Keep in mind that even if you delete your account, archives of anything public are likely to live on (for instance, at the Library of Congress).