If you look underneath the bumper in the middle, you will find that there are 3 push clips which can be carefully removed with a Flathead screwdriver, and on each far side of the bumper near the wheel arches you will see a tech screw, can't remember what type exactly.
The insert can then be carefully pulled off... but be very careful of the sensors. You will need to slide you hand up underneath the back of the bumper to carefully pop them out without breaking the wires.
It's fairly straight forward.