Due to inconsistent behaviour in how Outlook deals with removing add-ins, it may be that the icon for the web add PMA or New Outlooks remains. 

If this is the case, follow these steps:


  1. Close Outlook.
  2. Open the Run command by pressing the Windows key + R.
  3. Type %localappdata%\Microsoft\Outlook\HubAppFileCache and press Enter.
  4. Delete all the files and folders in the folder that opens.
  5. Restart Outlook and check if the add-in is now removed