Using classic Outlook for Windows in business environments
If it says its a PWA, it is a browser app - remove it from the browser menu > apps. If you mean the new Outlook, which is Outlook on the web in an app framework, this article has the instructions to revert to Windows mail or Outlook for Windows: https://support.microsoft.com/office/toggling-out-of-the-new-outlook-for-windows-preview-ec102b39-5727-418e-ae1f-a1805434640c