This article explains, how you can hide the Office add-in buttons in Outlook for Windows. This is useful, if you have installed both add-ins, to use the app with all features on all your devices.
Use Ribbon Customizations
Right click on the top ribbon and select “Customize the Ribbon”.
This will bring up a new dialog, where you can configure every detail of the ribbon. If you have both add-ins installed, you will notice that “Jira” appears twice.
To remove the Office add-in ribbons from Outlook, just click the second Jira entry and then “Remove”. This will hide the buttons, but still let’s you use the Office add-in from your phone or on the web!
If you want to revert this at some point, you can always use the “Reset” button on the same screen.