Cable (or cord): First, decide the mounting position and the final hanging height of the light, then the cable can be adjusted at the end of attaching the ceiling canopy. Simply cut off the cable to the needed length but please pay attention to allow a bit more left for connection to the supply wires.
Steel wire: Normally it goes through a small pin on the ceiling canopy. Simply pressing the pin, then you will be able to adjust it to be shorter by retracting into the canopy or longer by pulling it out (within the length range). When you adjust it to be shorter, you could also choose to cut off the redundant steel wire from the canopy end.
Chain: Determine the new length of the chain from the ceiling down and which link will be the last in line. Measure, Grip half of the link with a pair of pliers and use a second pair of pliers or an adjustable wrench to twist the other half, separating the link at the joint. Remove the unwanted portion of chain., where you wish the chandelier to hang. Then measure the fixture cord and chain on the chandelier and calculate how many links in the chain you should remove. If you want to well-protect the finish of the chain, you may cover it with a cloth.
Cut the chandelier cable/cord about 12 to 24 inches longer than the shortened chain to ensure that you have enough to weave through the links in the chain. Many people prefer to weave the wire through every second link in the chain, but this is a matter of preference.