How to erase the data from an iPhone I found that was reported lost by someone?

My friends were at the Seattle parade on Wednesday and they found an iPhone on the ground. It was being trampled and it was completely shattered and they didn't see anyone around them looking for it so they picked it up. They brought it home and asked me to take a look at it to see if I could erase all the data on it, which I knew I could. BUT they didn't tell me that it was reported lost using the Find My iPhone feature so it has a message on the screen that says "This iPhone has been lost. Please call me." and then it lists a number. I suggested that they call it since the person probably wants their phone back, but they just said that if I couldn't figure out how to erase the data then they would call but if I could clear the phone then they would just use it for music. When I slide to unlock the phone, it prompts me with the typical iPhone set up, asking for my country and to set up using Wi-Fi or iTunes and things like that. Once it gets to the iTunes screen, though, it asks me to enter the apple ID that was used to set up the iPhone as the only way to get into the phone and erase the data. Does anyone know how to get past that, or is that the absolute only way to get into the phone? I know I know I should just turn it in, don't judge please help!

Since the identity of the owner is known, keeping it is stealing. You are an accessory

Just call the number & try to get the person back their phone…

You are fighting a losing battle either way.

Since you know the phone is not there's, you're holding it for them makes you guilty of possessing stolen property, which is legally as severe an offense as theft.

" I know I should just turn it in, don't judge please help!"

I'm not judging.

Turn it in.