You don't need to remove the steering wheel to re-centre it in a Disco . . .
Underneath the car there is a steering link bar which connects the drop arm from the steering box to the nearside hub, it's the one at the front !!! this has a pinch bolt and threaded end, loosen the pinch bolt and rotate to turn the steering wheel in either direction.
This DOES NOT affect the tracking, this is done by the rear connecting bar between the two hubs !!!
(should you really want to remove the steering wheel, you need to disconnect the battery, wait AT LEAST 10 mins for the air bag to dis-arm, undo the 2 No torx screws underneath the wheel, lift off the air bag VERY carefully, disconnect the air-bag wires, undo the centre nut pull off the wheelusing a puller (not easy) re-align, and reconnect the air bag, refit, re connect the battery, enter the security code in the radio blah blah . . . in a nut shell, I think my method is a lot easier !!
Steve