The fingerprint sensor flex cable is glued onto the rear side of the screen with mild adhesive. In case you're having trouble with removing the flex cable, you can apply an iOpener to the front of the display to loosen the adhesive underneath.

Slide an opening under the upper end of the fingerprint flex cable.

Carefully work your way into the direction of the ZIF connector and use the opening pick to separate the fingerprint flex cable from the screen.