The ribbon cable is lightly attached to the headset with adhesive and the cable is connected with a ZIF connector. Consult Step 1 of the Recognizing & Disconnecting Cable Connectors guide (RDCC guide) for ZIF connector info.

Use the tip of a spudger to flip up the locking flap to release the cable. See pictures 2 and 3 to understand how the flap operates.

The cable is lightly adhered to the headset so be careful when removing it.

During reassembly, make sure to position the cable correctly. Latching the small black clip back on shouldn't require much force. If you don't connect the cable correctly, the headset's screen may stay black and the device will turn off after a few seconds.