There are four bolts (circled in blue) holding the regulator to the door, they are all 10mm head bolts, but the top two are longer

I used a 10mm deep socket on a 1/4 inch ratchet, but any 10mm wrench, spanner, or socket should work

in the second picture you can see the gear-quadrant of my old regulator hanging down, it's supposed to be up engaged in the winder gear teeth

It was at this point that I realised I could not get the old regulator past the window vertical track...

Notice I'm using a short prybar to prop up the window now (since otherwise it drops down) you could use a piece of wood or some other tool as well