Radio Volume Knob Removal

The volume knob (the push on-off part) on my 2001 Alero has broken and I would like to go to a salvage yard to get a replacement, but I can't figure out how to remove the knob. I thought I could just pull it off, but that doesn't work. Can I pry it off with a screwdriver? Any help would be greatly appreciated.

Does anyone know the part number and where to order one of these? I'm looking for a replacement to the volume knob, but I just need the middle part that says "volume," not the outer part that actually turns. But if you can only get them together as one part, that's ok.

I would also like to know how to remove it.