You can not clean it because Google stored your data forever. Even your deleted web browsing history, emails, whatever, they can have terms that after 30 days of deletion, you will lose those documents forever and they will not support you to recover such deleted data.
However, on Google side, they store it and did you read about the lawsuit against Google, that they stored users' web surfing history even in Igconito mode?
If you are serious with privacy, do it at the start.
This is why I am running Lineage OS on my phone, to stay out of google reach, this open-sourcei Android ROM comes with zero Google service and it is also one of the most secured ROMs out there, your data your rules.
Many people do like what Google is doing, not losing access to their data is why they choose Google, and in this case Google is doing it right, if you lost your phone your data is not lost, you will have access to it when you link your Google account again.
I remember when I sold my old phone years ago, I had to install an CM ROM on the phone in fear of the new buyer having access to my browser history, I felt like formatting the phone memory isn't enough for me, now I don't really care that much, because everything about crypto isn't available on my phone and computer anymore, I now have a hardware wallet but still, browser history has some big pictures about the owner.
My advice is for everyone to go pro by getting an air-gapped device, no need for an internet connection and there is no room for backing anything up into the cloud either, for crypto wise you will be save this way.