The idea of a super cookie is that you cannot easily delete it. It consists of replicas of the information on multiple places and if you delete some of these the information will be restored from the remaining places. Some possible places are:
- Simple cookies. These can usually be easily deleted. But one can make it harder if multiple sites cooperate so that the user does not know which cookies are relevant.
- Flash cookies, Silverlight cookies etc. Depending on the browser and OS super cookies might spread between browser profiles or even different browser types this way and maybe also between normal and private mode of the browser.
- HTML5 local storage.
- Caching information, for example by misusing Etag and/or Last-Modified headers. Caching is an essential part of a good browsing experience but these information can also be used to track you and restore the super cookie.
For a way more detailed and still not exhaustive list see Technical analysis of client identification mechanisms.
Based on how super cookies work the answer to your questions will probably be unpleasant:
How can I know if a website gave me a super cookie? Is there a guide line to follow?
There is no general guide since there are many different ways a super cookie could work. If you are curious about a specific site you might start with a freshly installed system (i.e. all plugins, cookies, cached data ... in initial state), visit the site and then do an analysis of the system what changed. I'm not aware of any tools which make a snapshot of all the ways information might hide and give you the difference between before and after visiting the site. And even then you would not know if the cached information are only used for speeding up access or also used for a super cookie.
How does this cookie report back to the website? (Would I see it if I inspect HTTP headers?)
Also lots of ways and with some of these (like use of caching information) it is not even clear if they are used for tracking or not.
Where it is stored? (I would like to see what it looks "inside".)
In lots of different places on your system, depending on the mechanisms used. This means that there is no single place you can look for the cookie.
How can I delete it(if possible)?
This depends on the mechanism used which you usually don't know.
The best would probably be to use a virtual machine with a browser and reset the machine to its initial state after each browsing session. You might also try with private/incognito surf mode or fresh browser profiles but some plugins might still be used to share information in this case.