I want to remove or delete all my old accounts, my old names, my old profile pictures, my old mobile phone number, my old passwords, my old ads and my old social media.
Not to be a joykill, but it would literally be easier and more efficient and have more of a guarantee of not having any skeletons pop out of the closet five years from now by legally changing your identity and moving.
To actually remove any traces of yourself from the Internet is impossible. Any site you were registered with has backups of their database. Depending on company policy and the type of information in the database, those backups can exist for up to 14 years.
The following links have some good information:
Truth be told, it is almost impossible ~ the longer you have been "present" on the internet the harder it gets.
You can remove things on the hard drive, but you can't remove everything you ever posted online.
You can delete your Facebook account (see http://en-gb.facebook.com/help/224562897555674), various Google accounts (see for example https://support.google.com/plus/answer/1044503?hl=en-GB) and so on, but once you have posted material online, others may have got hold of it and that is beyond reach. Additonally, sites like Google Wayback Archive (http://wayback.archive.org/web/*/google.com) keep a permanent copy of everything they come across, so there's a good chance at least some of your stuff will be there and you won't be able to delete it. Even those things you do remove may take a while to actually disappear (2-4 weeks seems to be the usual figure quoted).
Coming back to your hard drive, you can delete your user account (obviously, you'll need to have another account on the computer before you do this!) and then you can use a disk wiper such as the tool built into CCleaner to "wipe" the free space on the disk. This will cause any area that is not currently in use to be physically written over, so will be safe from retrieving.
you really can't ( not that i'm aware of). You would have to remove/close/cancel your accounts one by one and once you remove your account information (one by one) you'll drop off the search engines but to truly remove, I don't think it's possible.
for sites that have your information like mobile number and such, you can email/write them and ask that you be removed from their database.
Format hard drive? I'm not sure I understand the whole "remove or delete"? From where off your computer, network the internet?