They are cold water lines ( blue) and hot water lines (Red). They will drain ( via gravity) much of the water from the water lines, but not all of it. You need to open hot and cold faucets. You will need to blow out and /or add antifreeze if it gets below freezing where you live. I recommend you replace the screw on caps with 1/4 turn valves. This will make future draining much easier.
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