How to reboot an iPhone that's locked and has Find my iPhone mode turned on?

I found an iPhone, and I want to reboot it. But I can't quite do that at the moment because "Find my iPhone" is on. And it says I need to turn it off before it can be rebooted. But since I found the phone… I don't know the password, so I'm not able to access anything. Please help me if you can, I'll really appreciate it.

Just because you "found" it does not mean it is yours to keep and use. Think about how you would feel if you "lost" your iPhone and someone started using it… Turn it in to the Police department. Pay it forward.

It depends.

iOS 7 - can't do anything, so just turn it in to the lost and found
iOS 6 - hold power and home for three seconds, then keep holding home. Phone will be wiped of all data. This does NOT work for new phones (and for good reason!) so don't try.

Return the phone you stole to the police. If you want an iPhone, pay for it like everyone else.