Cooper Convertible (R52) L4-1.6L (W10) (2005)
If a springy resistance can be felt, press down lock as far as it will go and pull airbag unit (1) away from steering wheel.
Repeat procedure on opposite side.
For purposes of clarity, the procedure is shown in the next picture with the airbag unit already removed.
Press on lock (1) with a Torx screwdriver T25 (2).