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I want to remove New Outlook's access to my HM and OTLK domain accounts and remove New Outlook from my machine completely, without affecting the MAIL and Old Outlook accounts, as currently configured. Windows 10 (up to date)
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Uninstall the new Outlook - uninstall the app in Windows Settings: Open Windows Settings > Apps. Find Outlook (New) under installed apps and click the dots to the right of the name and choose Advanced options- then Uninstall. That will remove the app and the profile.
That should get you back in Mail (at least until they remove it) - if not, 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
The new Outlook is a work in progress - you can leave feedback and suggestions in the Feedback forum. Or, if a suggestion exists, vote for and comment on it. https://feedbackportal.microsoft.com/feedback/forum/89a8afa3-2e1c-ec11-b6e7-0022481f8472