Take off the cap on the back wiper in the middle and use a 8mm or 10mm socket to remove the nut (cant rememeber the exact size) Use wd40 to loosen up the wiper then take your time and be patient to remove the actual wiper arm.
the will need to remove the 2 t25 torx screws from inside the boot panel and pull the boot panel off. Then it's a case of disconnecting the wiper motor and using the correct socket to undo the rear wiper motor.