By disabling the rear auto brake you cancel your car's ability to perform braking interventions when you are reversing. Disabling the rear auto brake is only temporary. By default, the feature will reset to enabled between drives.
Important
Changing driver support settings
Make sure that you understand how changing the car’s settings affects its behaviour. It is particularly important when it comes to features that affect the level of assistance the car can provide.
In the parking view, press the rear auto brake button 
.
.Automatic braking when reversing is temporarily disabled.