I know how to show the developer options menu. How do I hide it again?
Clearing the data on the "settings" app will get rid of the developer options on the Galaxy Nexus (at least on 4.1. Not sure about 4.2), but that may only work on that device. It doesn't do it on my Galaxy S3.
Note: The above action clears the settings of the settings app, i.e. not actually importanty data per se. You should be fine doing this.
The only other known method to get rid of them requires root and deleting /data/data/com.android.settings/shared_prefs/development.xml.
See Where are the developer options in Android 4.2?
Edit: New CM10.1 added a feature to hide developer options when it is turned off.
Once you became developer you can't hide developer options from your mobile. But you can simply turn it off (Developer option will be there in Settings).