Remove the "new" Outlook installed 8/25/2026 without damage to Outlook Classic?

Yes. Removing the account from new Outlook does not damage Outlook Classic, because new Outlook and Outlook Classic do not share the same local data file.

If the goal is to stop using new Outlook and keep Classic Outlook:

1. In new Outlook, use the toggle at the top right and select Switch back to classic Outlook.
2. If the toggle is missing, make sure Outlook (classic) is installed. If it is not installed, follow the install instructions in You can't open classic Outlook on a new Windows PC.
3. If classic Outlook is installed but launch behavior still redirects to new Outlook, set this registry value to disable the automatic switch:
   • HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
   • UseNewOutlook = 0
4. If new Outlook was preinstalled and needs to be removed from Windows, it can be removed with PowerShell using Remove-AppxProvisionedPackage and package name Microsoft.OutlookForWindows.

Warning: editing the registry or removing provisioned app packages affects app launch behavior for Windows and can impact all users on the device. Use those steps only if the toggle is not sufficient.

References:

• Toggle out of the new Outlook for Windows
• Start new users in new Outlook
• Control installing and using new Outlook
• Outlook Classic and New Outlook - Microsoft Q&A