To un-install an iOS App:
  1. Force-Stop the app if it running (<Double-tap> the HOME button, then locate the app's window, <tap and hold> while you "swipe it up and to the right").
  2. Find the icon for the app you want to delete, and press and hold it for a few seconds.
  3. It (and all the other icons on the screen) will start to wobble gently, and a small cross will appear in a grey circle by each.
  4. Tap the cross, and then confirm you want to delete the app.

To re-install the iOS App:
  1. Go to the "Apple iTunes App Store”.
  2. Search for the App.
  3. Install the App

To un-install an Android App

The un-install process has evolved through several generations of the Android OS and recent versions require several specific steps in a specific sequence to be fully effective.

Many Apps will leave the App-Data (user-configuration information) on a device, and may leave the Cached-Data as well, during an App uninstall, then "conveniently" re-apply this data to the new install. 

Since this data may be corrupted or outdated it must be removed to ensure the new installation will not be affected.

The full procedure is as follows:

  1. Go to SETTINGS>APPLICATIONS>APPLICATIONS MANAGER.
  2. Select the app to be un-installed.
  3. Select "CLEAR CACHE".
  4. Select "CLEAR DATA".
  5. Select "UNINSTALL".

To re-install an Android App:
  1. Go to the Google Playstore and re-download / re-install the app.