Load it and it fingerprints your browser. You can add a signature to that fingerprint.
Make whatever changes you want to make to resist fingerprinting and reload the page. If it displays your signature then it has identified you, if not then your changes worked.
Ideally, every page refresh would generate a new unique fingerprint so the page can’t link you to the last time you loaded the page (which is what tracking is, essentially)
The site also displays all of the data that it can see, for advanced users
You don’t need to do any of this.
If your drive is not encrypted, then this won’t save you. It takes time to overwrite files and if your computer were the target of any adversary, they would simply unplug it immediately and then image it.
If your drive is encrypted, then you can just overwrite the headers that contain the key slots. This would take hundredths of a second.