With adjustable wrench in hand I set about removing the old regulator. First I removed the duct tape hold on the air hose. Judging from the amount of rust inside the break I'm guessing it's been cracked for a long time.
I placed the wrench around the body of the old regulator to get it off, as I couldn't turn it by hand. As soon as I applied pressure the entire regulator fell to pieces. After that everything came off easily. You'll want to save the female quick connect to use on the new regulator, if it's still in good shape.
I also saved the gauge. The new regulator came with one, so now I have a spare for another project. Sweet!