Open your Google Account at myaccount.google.com
Sign in to the account you want to erase
Go to Data and privacy
Scroll to More options
Select Delete your Google Account
Re-enter your password if prompted
Review the data and services that will be deleted
Check the confirmation boxes
Select Delete account
If needed, remove the account from your device settings
If you only want to remove it from a device, go to Settings
Open Accounts or Passwords and accounts
Select Google
Choose the account
Tap Remove account