Hi, my key won't turn the ignition lock. The ignition switch works but not the cylinder. How do I remove the cylinder? My is a 2001 Pontiac Aztek. Thanks; Miguel

The first thing you could do is get your hands on the correct part, with new keys cut.
Picture how that part will appear when installed into your vehicle's steering column.
This really is best left to techs with the correct tools and prior experience.
Do you want to continue?

If so, read through these steps first (individually, it's not that hard but read first):

Disconnect the battery negative cable. No special tools.
Disable the SIR system. No special tools, only knowledge.
Remove the steering wheel. You need special tools: adapters and pullers, and experience. This is major because when you reinstall the steering wheel, it has to be installed correctly to properly steer your vehicle.

Remove the tilt lever close out plate. Remove the retaining screw from the lower steering column trim covers. Tilt the trim cover down and slide rearward in order to disengage the locking tabs. Remove the lower steering column trim covers. Remove the retaining screws from the upper steering column trim cover. Again, all simple hand tools and some forethought.

Attachment 5929

Turn the ignition lock cylinder to the START position.
Use the 90° bent tip tool, as seen in the diagram, in order to push down on the ignition lock cylinder retainer, and then release the ignition lock cylinder to the RUN position and pull it from the housing.
Installation is basically the reverse. Make certain that the switch lines up when you reinstall the new lock cylinder.