There's 2 ways of doing it.

The small clip you already removed is for the outer cable only. The inner is still connected to the handbrake mech. To access it you need to remove the caliper and disc rotor and dismantle the entire handbrake shoe and linkage assembly inside the drum part of the rear brake rotor. It's quite involved.

The better way is to leave the hub assembly complete and remove the cable from the lever inside the car. Then remove the clips holding the outer cable and remove the cable with the hub. You can re-use the GD cable in your GC8.