i phone 4s as a gift 3rd party owner I received a second hand I phone 4s as a gift it has not been reported stolen or lost. being the 3 party owner how can I delete the account attached to this phone to activate it
Go to Settings / General / Reset / Reset All Content and Settings.
This will wipe the device and restore it to a factory-settings state.

If you do this, nothing will be left on the device (data, settings, accounts, etc) and you'll have a fresh start with the phone.