I have 3 Google accounts which have a bunch of auto-populated email addresses and contacts I have never intended to add to my Android.
I went to Settings > Accounts > Google > [email protected] > Contacts > Switched to OFF.
However, when I go back to the phone app, all of the garbage auto-populated email addresses are still there. And when I select one of them, it clearly indicates with a Google logo it was "synced from Google account".
I intentionally don't use Google stuff. I want it off my phone.
If relevant, I'm using Samsung Galaxy S6 on Android 5.1 Lollipop.