The de-ice system in the -60 is modular and is a kit, designed to be removed when desired. Typically FL, CA, and HI squadrons don't have them installed at home. If a deployment is going somewhere cold, they can get the kits from the Wing (or from on-hand if they've continued to manage the system).
I've seen cut de-ice harness like IBB said as well. It's an indication of a lazy Mx department, or lazy Wing. If you zip-tie the breakers and pull out the control box from the center console, you're not going to burn up the blades accidentally. Even the Bravos had the kits right up until sundown, they just took some grooming to get them to work.
As an aside, the SD to Vegas mishap aircraft had a functioning de-ice system and the crew turned it on after they started accumulating ice. Something I never heard debriefed whenever this mishap was discussed was that the crew started hearing a knocking-type sound after turning on the de-ice. The crew reported it but didn't seem to know what it was. Sikorsky said it was most likely the ice shedding off the blades and hitting the fuselage, and the sound is expected and means everything is working well.