The charger cable should be attached to the car when you arrive. To disconnect, unlock the car and press the button on the car next to the charger port to release, you can pull the cable out. The other end of the cable can then be unplugged from the charger and stored in the car boot. To plug it back in at the end of your booking you simply need to plug the cable into the car and charger, then follow the instructions on the charger to start.