Here's how it works. You have two data caches, one on your personal computer, related to your router's number and the transmitted data that's copied for Google's use.
You can delete your personal cookies, but the data on the other end of the line has no way to be tracked, there are, however, records of data requests from Google that go straight to their servers. The activity of these servers cannot be tracked, since their processes are internal and you'd have to go to the server to figure out what's going on.
Second, you might ask how they'd deal with the sheer amount of data that's being tossed around, which is a good question. The answer is "The Cloud" aka the peer to peer system that provides processing power and storage.
See, the internet is made up of a shit-ton of computers, including yours, and the recent singularity has been internet storage. Google Drive and so on. Google actually stores your data on the internet, completely accessible, and the only thing they actually have to store is the link to the generated site that contains your data. So each person has one link attached to your identity and name that stores all of your data.
Anyone can access this. The only security is that it was unknown. That is no longer the case.
Not only is google storing your data to sell, they're also making every private email, all information related to your bank, all information you put onto your computer, even the keys you're typing right now, in one file, on one individual site, using everyone else's computer to provide the data space and storage, completely and utterly accessible for all to see.
And the only reason I can't fuck you specifically right now, use all your data to deplete your money and send it to myself, to sign you up for whatever I want, to doxx you and send leftist hate groups after you, is because you're posting on this board, obfuscating your actual identity.
Remember your passwords.