How to delete or uninstall my com.lge.clock

I don't have an alarm set but can't stop the clock

The clock will run forever (since the time, of course, keeps changing). If you want to delete a system app like that, though, you'd have to root the phone. (Then run something like Link2SD to uninstall it. Titanium Backup can too, but Link2SD is free, TB isn't.) You might even find com.lge.clock in Settings > Apps, and when you're rooted, it may have an Uninstall button.