HTC One (M8i) delete your Google & Gmail account

OS: Android 5.1 (Lollipop); Sense UI 7

CPU: Octa-core (4x1.7 GHz Cortex-A53 & 4x1.0 GHz Cortex-A53)

Display: 5.0 inches, 68.9 cm²

Battery: Non-removable battery

Remove a Google account on HTC One (M8i)

If you are going to sell your old phone, you definitely need to delete your google account from your phone so that the new user cannot access your google profile and cause problems with google services.

What happens after deleting a Google account?
Emails, all data and content, including files and photos, will be deleted.
The phone user will not be able to use Google services that require an account (such as Gmail, Drive, Calendar, or Google Play).
You will lose access to subscriptions and content purchased through this account on Google Play and YouTube (for example, applications, games, music, TV series).

How do I remove a Google account from my phone?
Go to Settings on your phone.
After that, select the menu item Accounts and backup.
Select Manage accounts to access the accounts saved on your device.