1. If you are not willing for anything you post anywhere on the internet to last a long long time, do not post it.
2. If you are not willing to have your real name associated with your online presence, do not use any part of your real name as your screen name.
2a. In keeping with the above, never join any site that requires your real name or your personal information as a requirement for signing up.
3. If you are member of any site where you no longer wish to participate, vote with your feet- walk away.
4. Before walkng away change or delete any personal information, such as your email addy, your signature, I.M. information etc. Usually email addys cannot be removed, only changed. My friends joesmith and janedoe let anybody use their name in an email addy- joesmith@anyISP.com or janedoe@anotherISP.net.
5. Even when sites ban a user for life, they do not delete the associated account for the reasons cited above- holes in threads.