Is the dock key removable?

[Jumphog]

Ive just got a 'Thinkpad Dock' model 2631 from ebay - its great and having a PCI slot will be very useful, but I cant get the key out!
Ive downloaded the manual form IBM, but it just says 'look at the manual supplied with the dock' in several languages, so im none the wiser. Id like to not have to use the key as I dont need the dock to the laptop. As far as I can work out when the key is in the unlocked position it wont come out of the lock - is this normal?