You should see two bent wire type things with a bolt through each. One on each side of the carrier. Remove those, the wire bits actually engage the adjustmant collars and keep them from rotating once adjusted. Once those wire brackets are off scribe a line across the collar and some part of the housing next to the collar. Now use a punch and a hammer to rotate one collar loose. I usually just rotate one collar back two full turns and try not to have the carrier fall into my lap.
A piece of plywood under the diff is a good idea in case it does fall out and you can't keep it from hitting the ground.
Rene