Its amazing what you can find in the online AIP and AICs.
ENR 1.7 ALTIMETER SETTING PROCEDUREShttp://www.hkatc.gov.hk/HK_AIP/AIP/ENR/HK_ENR1.7.pdf
SID / STAR and Terminal Transition Route (TTR) Level Restrictionshttp://www.hkatc.gov.hk/HK_AIP/aic/AIC40-12.pdf
I understand your confusion with the latter. The instructions to controllers are just as vague as to how the cancellation should be phrased.
Some say, "Climb/descend
unrestricted to ...."
Others say "Climb/descend
now to ....."
Neither of which really fulfill the ICAO requirement to explicitly cancel the specific restriction (s).
And so the confusion continues......
If in any doubt, ask. We have about 1,700 flights a day through the Terminal Area now, so the chances of meeting someone above/below you are pretty good.
I can tell you now, descend early before MURRY without the restriction being specifically cancelled and you may be staring a Shenzhen departure or a Macau arrival in the eyes.