How to disassemble the nozzle?
Heat the nozzle to 210 degrees, making residual filament inside the nozzle automatically flow out. Afterwards, lower the temperature below 50 degrees, then wait until the nozzle is totally cooled down.
Tweak the nozzle to the point as picture shows.
Loosen the screw with a L-shape wrench.
Use 2 spanners: one for fixing at the upper location, the other for loosen the nozzle under, then take it off.