I understand the sentiment but why delete it? Just drastically cut back your "friends" and set your content filter then just don't use it. Its still a handy way of keeping in touch or finding an old friend if you decide you need to. I don't use it very much but why limit what you have access to?
Would you be comfortable with restricting how much information you share with the service and just keeping it around as a utility? Also,.would "deleting your account" actually take away the information they already have?
I was comfortable sharing my information with Facebook back in 2007. But as time has gone on I have become more cynical of their collection and use of personal data. I think this opinion was formed based on individual incidents (opening it up to search engines, changing of privacy settings) and largely uninformed media hype. Over the same period, I have become increasingly aware of my online 'footprint'. I want to get into politics later in life and don't want my opinions/photos/data being taken out of context in the future. Therefore, I prefer social media where my real identity is not disclosed.
Yeah, I never use twitter mostly because of format issues but I've got our just in case it comes in handy somehow.