Give someone else control as GM

I'm about to wrap up a campaign on Google Hangouts. One of the group members will take over.  Apart from having him start his own hangout campaign, is there a way to give him GM rights/access to mine?

You can promote someone to GM, on the Campaign page. Just hover over their picture there However, you will still be the owner and certain things only you can do. I've no idea if starting the game in a Hangout is one of those. But if you're about to wrap up anyway, and the player is starting a new campaign it's probably better if he makes his own game just to avoid any problems.