What service are you performing on it? Theres really no need to remove it for most tasks except for changing out the caliper. Use pliers to depress the parking brake lever and relieve cable tension. Then, grip the end of the brake cable with locking pliers and disconnect the cable from the lever. Then detach the parking brake cable retaining clip and remove the cable from the caliper.
And if you do want to separate the cable from the caliper while leaving the spring alone you can easily bend back the part that is curled around the cable end holding the stay in with a channel locks. Then IIRC a clip holds the cable in the caliper where the rubber bushing is. Remove the clip and pull out the cable.
Tip: Good idea anytime doing rear (or front for that matter) pads is to pull all 4 caliper slide pins and clean and relube them. You can use brake or wheel brg. grease but i prefer anti-sieze compound.