you have to remove the whole lock core which is why the chrome face is always broken off , you need to use a key or pick the lock into the locked position then using a paper clip you have to poke into a small window in the 6 Oclock positon & depress the lock retainer & pull the core out of the housing , this is obviously much easier to do if you have the key for the lock , or take it to a locksmith
Use a jewlers screwdriver and find the tab at the front of the cylinder, looking thru the window.
Angle the screwdriver and depress this tab. While holding the tab in, PUT THE KEY BACK IN.
If you depress the worng tab, the key will not go back in.
Once the key goes back in, you can stop depressing the tab, as the key holds it down. If you can, try to look inside the window to confirm that the front tab is down.
Pull the cylinder apart.