I've been online society for several years. Being online is like having second life ( Virtual Life ~ VL ). Having a new nick and you can have multiple nicks. Some people use their real name and when they did a mess, they are forced to quit. Another extreme is some people use multiple nicks and later they wasted their time over multiple VLs.
Most of the people staying online don't want to exposed their real life ( RL ). They hide their profile, they don't meet anyone outside, they don't show/post their photo online. They don't even say where are they staying and what profession they are doing.
Some still want the 5 minutes fame for nothing. Some try to link with some famous online people and some try to be follower of certain online-celebrity. Myanmar blogger has some habits to put friends' blog urls in side bar. Some are putting real friends, some are putting the urls of blogs they used to visit. But some are purposely put well known people's urls. Some try to quote a lot and say "Yes" a lot to certain people who they think they were famous.
Some people even did certain things which they don't do in their real life. Some do vandalism in order to get some fame. Some becomes crackers and use all kinds of hacking techniques from hacker's forum. Some even end up in jail. Some jumps into social network and did something annoying to the existing peoples to get notice.
From my point of view, all kinds of network can be defined as "Social network", including Chat Rooms, Message Board, Forums, Blogs, People's Network, Directory services and news groups. The similar properties for "Social Network" is vast amount of people are involving in it.
Some of the networks are not reliable, like chat rooms. But the information on the chat rooms are voltile ( except saving and logging ) when some are having permanent information which nobody can remove. Some of the networks has no way out, yes, you can register but you can't close/cancel/de-register your account. Some network doesn't sell/transfer your profile information until you try to close/cancel/unregister your account.
Some of the network use your email to communicate your contacts ( friends ). Some network ask you to invite more and more people. Some just ask to give your friends' email and they spam them for you. Some of them even ask you to surrender your email address and password, so they can spam the whole list of your contact. They called this as marketing, simple.
There's always a couple of stupid people in your friends and they do have your email address in their contact. Next thing you know was .. your mail box was filled with unread/unwanted invitation, daily. If you don't filter them, then you can't even read normal emails without searching inbox.
Whenever you are registering a social Network .. use your nick. If you want to use your real-name then try to have complete seperate accounts from your nick. Don't merge them as much as you can. The best practice is to have dummy email address, use that whenever you register to any website.
If you want to cancle, remove, delete or don't want to exist in that society, First thing to remember is .. Don't request the domain controller or website admin to remove/delete your account. Account deletion is a mess, in terms of marketing, social and technical point of view.
Some of the forums let you delete your post manually. Some lock after certain time. But most of the people's site let you change/remove photos and edit your profile. So what you can do is .. remove your photos, change your avatar and other profile particulars. If you can delete, delete all the comments, private messages and all other inter-messages between all of them. Then remove all your contact and friends in your profile. Change the profile setting to private, put your public photo/avatar to Black/White wall paper.
Then leave the network. But make sure you are the controller of your account and make sure your account was still active until removed by the site for long term inactiveness.