If the key can be put into the first position then there is a special tool used.
There is a tiny hole if you look closely at the metal part of the cylinder.
The tool is basically like a paper clip, or a piece of stiff wire.
You put the key in the first position, insert the paper clip and pull out the cylinder.
You may need to remove the outer plastic ring first, -this is an antenna ring-
The removal of the cylinder is kind of tricky, but if you do it just right it will slide out.
Thanks.
BMW Technician
Master BMW and Master ASE Certified