HOW TO REPLACE THE COOLING BY-PASS HOSE?

The truck is losing all of it's water from a hose that wraps back around the engine and connects to the bottom of the cooling reservoir. This bypass is made of steel tubing and hose connections. I can't figure out how to replace this hose. It ssems to one piece of steel tubing going down the passsenger side of the engine then around the back of the engine then back down the side of drivers side of the engine where it changes to a hose. It's seem very hard to remove this hose.