I did it all the time when i was servicing bottles, you only need to unscrew it slightly to generate a small leak enough to empty the bottle in a few minutes, it's not like when the disc blows out, obviously the more you unscrew it the faster it will vent.Undoing the burst disk would release pressure - but that’s not something I would fancy having high pressure air spraying out of the side of a regulator whilst holding it and a tool