For the very first time in six years I own an iPhone, I've used restrictions in settings, to disable app deletion from my device. Yesterday it happened to me that my phone was unlocked in my pocket and it deleted two apps accidentally.
But now it will be more trouble to delete an app when you want to do so. Just make sure it's off before poking it in your pocket.
WIN!
You can never hide your phone calls or messages from the NSA.. You can hide them from others by using a passcode that only you know or by deleting them regularly from your phone