Disable an app for Outlook
If you don’t want to use an app for Outlook, you can disable it so it won’t show up in your messages. If you want to use the app again later, enable it. See Enable an app for Outlook to find out how.
In Outlook, click File > Manage Apps.
In Outlook Web App, click Options > Manage Apps.
Click the name of the app, and then click Disable.