The good news is that in iOS 7, a person can’t disable the Find my iPhone feature without entering Apple i.d. and password. For older iOS users, you can follow steps below to make find my iPhone app more secure.
When the “Find My iPhone” app is downloaded and installed, the phone screen when settings>iCloud is selected should look like this:
Photo 1 To secure the phone, an Auto-lock interval should be set and Passcode lock and Restrictions should be enabled. The phone screen when settings>general is selected should then look like this: Photo 2 If the phone is stolen before the Auto-Lock interval has expired, the thief may selectsettings>iCloud to display the screen of photo 1 and turn off the “Find My iPhone” app. Now the phone cannot be tracked and none of the features offered by the “Find My Phone” app are available. To guard against this, select settings>general>restrictions, scroll to down Privacy and tap on Location Services. As part of setting up of the “Find My iPhone” app Location services is turned on for that app as shown here: Photo 3 In settings>general>restrictions>Privacy, tap on Location Services and then on the next screen tick “Don’t Allow changes”. Now when settings>iCloud is selected, the screen looks like this: Photo 4 In the screen shown in Photo 4, the entry for the “Find My iPhone” app is greyed out and the app cannot be turned off unless the Restrictions password is known and Privacy in Restrictions for Location Services is changed to “Allow Changes”. With everything set in this way, if the phone is stolen and the Auto-Lock interval has not expired (or one has not been set), it is now not possible for the thief to select settings>iCloud and turn off the “Find My iPhone” app. To be able to turn off the app the thief would need to know the restrictions password and change the privacy settings in restrictions for Location Services to “Allow Changes”. All of the above is applicable to iOS devices running iOS 6.1.4 or earlier and which have iCloud service. For devices using iOS 7 with “Find my iPhone” enabled and set up in iCloud, the settings mentioned above can still be adopted but are no longer really necessary as turning off “Find my iPhone” now requires the entry of the Apple ID password of the iCloud account to disable it. If you try and disable the app a screen like the following will appear: