Just syphon some out, you only need to empty the header tank.

As Daniel said, needle nose pliers are the way to go, open them up till each tip reaches two of the small holes, then twist anticlockwise.
Once you have the white ring out, the float assembly just pulls straight out.

See below

If you realy must just disconnect plug and bridge the two terminals and the light goes out...But I'd rather have low coolant senser...Try cleaning it...

Cheers for that madmax... thats one way to do it. lol
Will give it a go when I get a new sensor.


Cheers

how much did the new sensor and tank cost mate?

Well, I personally payed some friggen crazy amount from ford, DONT DO IT!
I know its from vic, but get it sent up, WELL worth the saving, email or pm xr8 dismantler or neo_nick at Ferntree Gully Auto Salvage in melb here, they are one of our sponsors n have a very active forum section.
They should be able to do you something HEAPS better than ford price so im told.

PS: you will be happy you did, looks brilliant to see it like new again.

I got a new overflow tank from FTG for $35 that looks only a few weeks old, much better than paying big $$$ from ford.

New looking ones from wreckers are going to be fairly rare, it was only by luck that it was there so I thought i'd snap it up.

New ones from ford are about $130 I think

I'd like to add my advice about this very common problem.

The sensor is a VDO unit and it costs around $100 to replace. Do you need to replace it ? Probably not!

Make sure the coolant is cold!
Take a pair long nose pliers and insert the tips inside the white plastic plug.
Turn anticlockwise until the plastic cap comes out.
No coolant should flow at this stage as it is kept inside the tub by a seal pressed by the switch.
Gently grab the black plastic end of the sensor and gently pull it out.
Have a clean ice cream container ready to collect the coolant, You will collect less than a pint.
Gently remove the sensor unit
Inspect it. It will be a little dirty so give it a good clean (use engine degreaser or diesel fuel to clean it well)
The MOST LIKELY problem is that the white (now yellow) plastic will be filled with coolant.
Search for the small crack by gently squeezing the bulb between your fingers
you will see coolant leaking from the crack.
Now empty it and either fix it or go and and spent $100 for a new unit.

To fix it , use a soldering iron, gently rub it on the crack and it will seal it permanently. If you want to do a top job you can get the tip form a caulking sealant tube and gently melt the tip on the soldering iron
Now apply the plastic to the crack.
Use a small file to ensure the surface of the plastic weld is smooth

The seal will more than likely strill be inside the round hole where you removed the sensor
insert the sensor with finger pressure inside the hole and screw back the plastic lug. This will push the sensor in its' correct position

Fill up with coolant(I refilled it with the one I collected) and enjoy turning on the ignition without the low coolant warning light turning on...