For iOS:
Find the Shell App on your home screen
Hold down the Shell App for a few seconds until it starts vibrating. There is now an X at the top of the app.
Click the 'X' to remove the app.
Go to the Apple App store. Find and install the Shell App again.
Open the Shell App and log in.
For Android:
Go to the application manager. These can be found at Settings > Applications > Application Manager
Scroll through the applications and select the Shell App
Choose to delete
Go to the Google Play store. Find and install the Shell App again.
Open the Shell App and log in.