to remove the nozzle - heat the nozzle to about 180.
grip the heat block CAREFULLY ! with pliers. making syre to avoid wires and tape.
And unscrew the nozzle with a small spanner.

Oh yeah remove filament first.

The cheap ctc rep clones do seem to be prone to this.

To completely dissesemble that extruder is really easy.
See the two bolt/screw heads at the bottom of the fans.
Renove those and everything else just comes apart.
Keep an eye on where the two white plastic spacers go - no matter how aware of them you are the bloody things always fall off and roll away somewhere.

The bolts pass through the fan, spacers, heatsink and then a metal block and then into the stepper motor. They basically hold everything together with the metal block and carriage the anchor.

You can remove the nozzle without heating it - I used to do that. But it's much easier if heated. I suppose the aluminium expands more than the brass.

I have a pair of turbo pliers that clamp with straight, parallel jaws, that work really well. https://www.taiwantrade.com/product/...-1412669.html#
I have no idea where they came from - but look around they are perfect for doing stuff with 3d printers :-)
I think I might have got them from a client at some point. But they are perfect for gripping a heat block :-)