Stopping Forwarded Calls

So yesterday I was passed out and my friend’s phone died and he figured it’d be a good idea to forward all his calls to my phone. I have no idea how he did it, and I didn’t even know it was possible. Anyway he never undid it and I’m getting all these calls and messages with his random friends asking who the hell Josh is or why did you change your name and all this fun stuff.

I can’t get a hold of him to turn it off as calls to him just end up on my phone. Anyone know how to make this stop from my end? It’s getting on my nerves.