Disable all the tracking services from the Google Privacy panel: https://myaccount.google.com/privacy
You can clear your “history” from My activity: https://myactivity.google.com/myactivity
Also, Google Dashboard shows you an overview of your Google-related accounts and data. You can remove the subaccounts you don’t use (e.g. Blogger or Google Plus profile): https://www.google.com/settings/dashboard
Disclaimer: Removing the data from Google doesn’t mean you magically remove all your data from Google itself or other corporations or agencies they’ve cooperated with (i.e. NSA). But it is a manifest to claim your right to privacy and may prevent future unscrupulous and unmoral data recollection.
After such scrutiny, you may want to learn how to live without Google: livingwogoogle. A good starting point would be taking a look to this other thread:
Finally, you can consider switching to FP Open OS: #software:fp-open