Locate the App on your device.
Press down on the icon for the App until an "x" pops up in the upper left hand corner. 
Tap on the "x" and then on the "Delete" option that will appear.
You may now go back to the App store to redownload the App. To do so, click on the App Store icon.
Once in the App Store, search for "GMG Savings".  You will then click on the "Get" button to download.  From there, select "Install".