I'm on mac as well so I can help you out
1. Once your phone has booted, you'll have to turn off your phone. Once it's off, hold Volume (-) and the power button. Then using the volume down button go to Recovery, press the power button. You are now in the clockworkmod screen.
2. To remove cityid, make sure you have the android SDK (available from Google). I would rename the folder that you unzip to just "sdk". Then open up a terminal. Right now my sdk folder is in downloads, so in terminal type "cd downloads/sdk/tools" without the quotes.
Plug in your device. From the clockworkmod recovery main menu select partitions menu, then select mount /system.
Then in terminal type in "./adb shell"
then type in "mkdir /system/app.disabled"
Then type in "mv /system/app/CityID.apk /system/app.disabled/"
Then simply type exit in terminal, and umount /system on your CWM Recovery screen, press the power button to bring you to your main screen, then press Reboot phone.
I hope this helps!