Slide the tip of an opening pick underneath the right edge of the graphite foil covering the NFC antenna.

Carefully start to separate the graphite foil from the back cover by pulling it upwards and slicing the adhesive with the opening pick.

In case you want to reuse the graphite foil and the adhesive becomes hard to peel off, it has most likely cooled down. Use your iOpener to reheat it and to prevent it from tearing.