It's not easy to find the demolition date of the Hammerhead Crane, Hung Hom. Fortunately, in the early 1980s frequent aerial survey flights were performed that are accessible at the website of HKMS 2.0. These were executed at different flight altitudes, therefore some photos have poor resolution.
In this compilation the top row shows the crane, while it's already gone at the bottom row. So the demolition date should be between May and October 1982.