How can I reset an Iphone 6 with no passcode or itunes?

I'm an uber driver and i've been holding onto this iphone 6 someone left behind for over a year now. I'm deciding to sell it but i want to unlock and reset it. I have downloaded Itunes onto my computer but when I tried to connect it I get an error message 0xE8000015. The phone has a passcode so I can't get into it that way.

What are some solutions for unlocking this phone and resetting it?

Apple destroys phones… The 6s esp started the trend of BRICK status.

You can put the phone into DFU mode by holding the volume up and home button when powering it on to reset it via iTunes.

However, if the person set up their iCloud account on the phone then it will ask for that email and password after the reset to activate it. Without those the phone is useless.

You don't the whole idea of what you are seeing is designed to make stolen phones valueless!

You can't. It's the basic anti-theft system, only the real owner can ever unlock and reset / reactivate it.

Also it is stolen property and permanently traceable by the serial numbers.
You should have handed it to the Police.

Failure to do so is criminal theft - "Theft by finding" or "Theft by omission" etc., depending on the country and local laws.
It's no different in law to "finding" something in someone else's pocket…

Let's change some words:

"I'm an smartphone user and i've been holding onto this car someone left parked on the street I was walking down for over a year now. I'm deciding to sell it but i want to unlock and reset it. I have downloaded keyfob codes onto my computer but when I tried to connect it I get an error message 0xE8000015. The car has a passcode so I can't get into it that way."

Maybe someone will drive away with your uber-car with the same mentality as you have.