On an Android phone, Gmail app is showing emails from my Gmail account despite that I have never authorised that app to access the account.
This started when [EDIT:] I logged-in to Google Play Store , and then got a new email notification from a Gmail app installed on the same device but never accessed by me. Accessing it shows it has emails of mine.
I tried removing the Google account from the device and disabling the Gmail app following the instruction on Google Support - Sign out of Gmail, but when reenabled it, it still shows my emails.
How can I remove my emails from the Gmail app?