Only social media addicts would probably appreciate my efforts to disengage from so many networks and services. "Normal" people would not be impressed, since they would not have signed up for so many in the first place. In this effort I'm aided by the fact that I keep careful lists of whatever services joined, and can therefore go through the list and eliminate networks one by one. Note: another method is to google your name or username and see where you are listed. Sites like 123people.com are also good places to check.
Sometimes it's really quite hard to find the "delete account" button. It's either on a well-hidden unlinked page or requires an email to the company (if you can find their contact information). It's possible to search for this information on the web, but someone should create a purpose-built site that accumulates all the relevant information on how to disengage from all the networks. It could be an interesting project.
For networks that are a part of Facebook's or Twitter's ecosystems, or log into one's email (like threadsy.com), the easiest thing to do is remove permission for them to log into these services. Some networks, like Identi.ca, have recently introduced "remove account" buttons in their settings.
Despite all the time spent deleting networks, there will still be a lag before search engines catch up with you and delete old posts from their cache. Some content farms or aggregators will probably never delete you from their records until they go bust. You can only pray for their speedy demise.