Rotate the tensioner counterclockwise.
Push the spring clip toward the tensioner to lock the accessory drive belt tensioner in place.
You might find a free repair manual here: http://bit.ly/autozone_repair_info
Any suggestions on how to access the tensioner in my 2005 Freestar. There isn't room there to use a socket and, with a plain old wrench head on the extender bar, there's no room to turn it. Hopefully, something simple I'm just missing?