If you can't beat them, join them. In other words, if you can't delete all you online info, you can create several identities and create as much confusion as possible surrounding who you really are. For example, create several Facebook accounts with your name and the five addresses you've chosen for your five alias identities. Or revisit every site you can remember where you filled out a form requesting your personal data. After you login, edit the form and fill it with the data from one of your aliases.
No. 7: Don't delete, overwrite
Never try to delete anything, always edit and resave the edited data over the old data. All of your information is digital and controlled by programming code that's always looking for "new" files. These systems are programmed to save all the deleted files, but edited files; that is, files with the same filename are backed up onto servers on top of (that is, they overwrite) the old files with the same filename. Old versions of the edited files are kept for a few months (more or less, based on the company policies) but, eventually, the older edited files will disappear.