Congratz on lacking a spine. So your cousin forced you into deleted the memory, didn't you even question that or realise what it would mean? You just stole a phone, pure a simple. The owner even goes and texts you, but you damage their property and keep it for yourselves, even when it's clear they need it to simply get home. Don't go by that foolish rule of finders keepers, it was still their property and you could of returned it at no loss (You could have been given a reward if they were greatful, but that shouldn't be your motive).
I'm sorry but you're a fucking idiot in my definition, you say you've had your own phone stolen, but you think it's fair game to do it to someone else? What a dick.