Ignition cylinder removal help

I'm having trouble removing the ignition cylinder , I just can't figure out how to disconnect it . Can someone please help me out ?
I need to do this because I lost the keys to my car and I need to get the cylinder reprogrammed to match my new key .
All help is appreciated .

If you take your vin number to GM they should be able to make a key. Some locksmiths will also do it for you.