Find My iPhone is great feature for tracking your lost or stolen phone or iPad (NY Times tech columnist David Pogue recently used it to find his stolen iPhone). The downside is that all a thief has to do to turn off tracking is change that setting on your device. Keep that from happening with these steps.
First, you should password protect your iPhone or iPad to make it harder for a thief to get into it in the first place. Instead of the standard 4-digit number passcode, use a stronger, longer passcode that can contain other characters. Head to Settings > General > Passcode Lock , and turn off "Simple Passcode" to get the more complex passcode option. Even if you add just one extra digit, you'll boost your security.
Next, go to the Restrictions settings (also under the General settings) and choose to "Enable Restrictions." You'll be prompted for a 4-digit PIN (this is different from your device's main passcode lock above, but a special one just to change Restrictions.)
Then, under the Privacy section on the Restrictions page, tap "Location Services" and tap "Find My iPhone." Make sure Find My iPhone is on and turn off the "Status Bar Indicator" to hide the location tracking from thieves.
Finally, go back to the "Location Services" section and select "Don't Allow Changes."
These settings changes should make it harder for a thief to steal your iPhone or iPad and get away with it.
[via About Network Security]