Turn off the electrical power to the room by flipping the switch in the breaker box.
Use a ladder to reach the top of the pendant lights where they are attached to the ceiling. Unscrew the washer that is securing the cord to the canopy and then slide the canopy down the cord. If the canopy is attached to the crossbar underneath, unscrew those screws as well before you remove the canopy.
Gather up the cord or chain and coil it up inside the housing in the ceiling where the electrical box is housed. Coil until you have reached the desired hanging length. You may have to have a friend measure from the bottom of the lamp to the work surface as you coil the cord, so that you know when to stop coiling. Uncoil the cord if your lamp was previously hanging too high.
Slide the canopy back up the cord and screw it back into place. The canopy should neatly hold and hide the coiled cord or chain.