Hi,
I'm trying to change the crank position sensor o-ring on my 2003 mini R53. I have access to it, but I can't figure out how to disconnect it and I don't want to break it. Which way does the red thing move?

 

I realize that since I have the radiator and everything else off the front of the engine I didn't really need to disconnect the crank position sensor from the wiring harness.

I just unscrewed the 10 mm head bolt and pulled the crank position sensor out and changed the seal with it still connected to the wiring harness.

 

As usual, ModMini video on the subject helps a lot:

That red plastic moves the same way as the one on the coil does: train on that one before, because it's likely in good shape and easily accessible.
But yeah, unscrewing the bolt to pull the sensor first is the way to go. Removing that clip while the sensor is on the car is unnecessarily hard, with the lack of access and oil everywhere. It's super easy to unclip once the sensor is out. Or as you found out, replace the o-ring without even removing the sensor.