Uninstall & Reinstall Issues

Will Outlook Data Be Lost When Replacing Microsoft 365 with Office 2021?

Huma Ashraf Ch Oct 13, 2026 868 views

Question details

The user wants to know if replacing a Microsoft 365 subscription with a perpetual Office 2021 license will result in the loss of Outlook data or OneDrive files, and if uninstallation is required.

How to Replace Microsoft 365 with Office 2021 Without Losing Outlook Data

Product: Microsoft Office
Device & OS: not provided
Scenario: Switching from a Microsoft 365 subscription to Office 2021.
Observed behavior: The user needs to transition software licenses and versions without triggering data loss, profile resets, or licensing conflicts.

Before you start

Verify that your current OneDrive storage usage is below the 5GB free limit to prevent cloud file deletion after your subscription expires, and ensure you have your Office 2021 product key ready.

Solution 1Recommended

Safely Uninstall Microsoft 365 and Install Office 2021

Use this method to correctly remove Microsoft 365 licenses and install Office 2021 while preserving your local Outlook data and accounts.

Uninstalling Microsoft 365 before installing Office 2021 is highly recommended to avoid licensing and installation conflicts. The uninstallation process typically leaves your local Outlook data (.pst and .ost files) intact, but exporting a backup ensures zero data loss.

Export your Outlook data

Open Outlook, go to File > Open & Export > Import/Export. Choose 'Export to a file', select 'Outlook Data File (.pst)', and save a backup of your current mailbox data.

Uninstall Microsoft 365

Download and run the official Microsoft Office uninstall support tool. Select your Microsoft 365 version from the list and follow the prompts to completely remove the software.

Restart your computer

Once the uninstallation is complete, restart your computer to clear any lingering registry files or background services.

Install Office 2021

Log into your Microsoft account on the official website, navigate to your Services & Subscriptions page, and download the Office 2021 installer. Run the installer and activate it with your linked account.

Import Outlook data (if needed)

Open the newly installed Outlook. If your profile was not automatically detected, go to File > Open & Export > Import/Export and import the .pst file you created in step one.

Safely Uninstall Microsoft 365 and Install Office 2021

OneDrive Storage Limits: Your OneDrive files remain in the cloud. However, when your Microsoft 365 subscription expires, your storage capacity reverts to the free 5GB allowance. Files exceeding this limit may eventually be deleted by Microsoft if the account remains over quota.

Free Microsoft Office alternative

Switch to WPS Office for a Hassle-Free Experience

If you want to avoid complicated version upgrades, subscription expirations, and licensing conflicts, consider switching to WPS Office. It provides a lightweight, entirely free office suite that opens your existing documents flawlessly.

1. Download the software: Visit the official WPS Office website and download the free installation package for your operating system.
2. Install WPS Office: Run the installer. The process is quick and won't conflict with existing Microsoft Office files.
3. Open your files instantly: Double-click any existing Microsoft Office document to open, edit, and save it seamlessly in WPS Office.

Fully compatible with Microsoft Word, Excel, and PowerPoint formats (.docx, .xlsx, .pptx).Free and lightweight alternative to Microsoft 365 without recurring subscription fees.Familiar user interface makes transitioning completely seamless and requires no retraining.Built-in PDF editing tools for comprehensive document management.

microsoft office alternative - wps office

Frequently Asked Questions

Do I absolutely have to uninstall Microsoft 365 before installing Office 2021?

Yes. Leaving both versions installed can cause licensing conflicts, application crashes, and issues with default file associations. Uninstalling Microsoft 365 ensures a clean environment for Office 2021.

What happens to my Word and Excel documents when replacing Office versions?

Your local Word, Excel, and PowerPoint files will remain entirely unaffected. Uninstalling an Office application does not delete the documents you have created and saved on your hard drive.

Will my Outlook contacts and calendar events be preserved?

Yes, Outlook stores contacts and calendar events in the same data file (.pst or .ost) as your emails. As long as these data files are not manually deleted, your information will be available when you sign back into Outlook in Office 2021.

Installation & Activation