DELETED IT. YOU CAN TOO.
Step #2. Now, open any conversation and then tap on the Apps icon to access the apps bar.
Step #3. Next, you need to swipe from the right right to the left to get to the end of the app bar.
Step #4. Next, tap on the More button.
Step #5. Up next, you should see the list of all of your installed iMessage apps. Find out the app you wish to get rid of and then swipe left on it. Then, tap on the Deletebutton.