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How to Uninstall Office Completely Before Reinstalling With a New Key
Table of Contents
By MCAKey Technical Team
You just bought a new Office product key. You go to activate it and get hit with “This product key has already been used” or “We found another Office product on your PC.” Frustrating. You thought you removed the old version, but Office has a way of leaving pieces behind that block your new installation cold.
The problem is that a standard uninstall through Settings or Control Panel rarely removes everything. Registry entries stick around. Licensing files hide in AppData folders. And those remnants tell your new installer that Office is already present. To uninstall Office completely before reinstalling with a new key, you need to go deeper than the typical uninstall process.
I have walked hundreds of customers through this exact scenario. The good news: once you know which tools to use and in what order, you can get a genuinely clean slate in about fifteen minutes.
Quick Answer
Quick Answer
To uninstall Office completely before reinstalling with a new key, download and run Microsoft’s official Office Removal Tool (sometimes called the Support and Recovery Assistant or SaRA). This tool removes all Office products, registry entries, and licensing data that a normal uninstall leaves behind. After running it and rebooting, install your new Office version fresh and enter your new product key during setup.
What Causes Office Installation and Activation Conflicts
1. Leftover registry keys from previous installations. When you uninstall Office through Control Panel, the core program files go away but registry entries under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office often remain. These tell the new installer that a licensed copy already exists.
2. Residual licensing tokens in the LocalAppData folder. Office stores activation tokens in hidden folders. If these are not removed, your new key may conflict with the old license data, triggering error 0x80070005 or “Product Activation Failed.”
3. Multiple Office versions installed simultaneously. Running Office 2019 alongside Microsoft 365 (or Office 2016 next to Office 2021) creates overlapping components. Microsoft explicitly warns against this, but it happens constantly when people upgrade without cleaning house first.
4. Corrupted Click-to-Run installation files. Click-to-Run installations update themselves in the background. If an update was interrupted, the installation can enter a half-broken state where neither uninstall nor repair works properly.
5. Third-party uninstallers that miss Office-specific folders. Tools like Revo Uninstaller catch a lot, but they do not always know about Office’s unique folder structure under C:\Program Files\Microsoft Office and C:\ProgramData\Microsoft.
How to Fix Office Installation and Activation Conflicts
Solution 1: Use Microsoft’s Official Office Removal Tool (Recommended)
This is the method I recommend first because it handles Click-to-Run, MSI-based installs, and Microsoft 365 subscriptions all at once. Microsoft maintains this tool specifically so users can uninstall Office completely before reinstalling with a new key.
Download the tool from Microsoft’s Office support documentation — search for “Uninstall Office from a PC” on that page.
Run the downloaded SetupProd_OffScrub.exe file. Accept the license terms and let it scan your system.
When it lists the Office products found, select the version you want to remove (or “All” if you want a complete wipe).
Wait for the removal to complete. This typically takes 5-10 minutes.
Restart your computer when prompted. This step is not optional — several registry changes require a reboot to finalize.
After the restart, your system should be free of Office. You can now install your new version and enter your new product key.
Solution 2: Manually Remove Office Using Command-Line Tools
If the removal tool fails or you prefer command-line control, you can manually uninstall Office using built-in commands. This approach works well for Click-to-Run installations.
First, open Command Prompt as Administrator by right-clicking the Start button and selecting “Terminal (Admin)” or “Command Prompt (Admin).”
Navigate to the Click-to-Run folder:
cd "C:\Program Files\Common Files\Microsoft Shared\ClickToRun"Run the uninstall command for your Office product. For Microsoft 365 or Office 2021:
OfficeClickToRun.exe scenario=install scenariosubtype=ARP sourcetype=None productstoremove=O365ProPlusRetail.16_en-us_x-none culture=en-us version.16=16.0WARNING: The productstoremove value varies by Office edition. Replace “O365ProPlusRetail” with your actual product ID (e.g., “ProPlus2021Retail” for Office 2021 Professional Plus).
If you are unsure which product ID you have, run this command first to list installed products:
OfficeClickToRun.exe scenario=install scenariosubtype=ARP sourcetype=None productstoremove=? culture=en-usReboot after the uninstall completes. Then verify removal by checking that the folders under C:\Program Files\Microsoft Office are gone.
Solution 3: Clean Up Residual Licensing Data Manually
Sometimes the uninstall completes but licensing conflicts persist. In my experience, this happens about 20% of the time when switching from a subscription to a perpetual license or vice versa.
Open Command Prompt as Administrator.
Navigate to the Office licensing folder:
cd "C:\Program Files\Microsoft Office\Office16"If that folder does not exist, try:
cd "C:\Program Files (x86)\Microsoft Office\Office16"Run the license cleanup script:
cscript ospp.vbs /dstatusThis shows all installed licenses. Note the last five characters of each product key listed.
Remove each old license by running:
cscript ospp.vbs /unpkey:XXXXXReplace XXXXX with the last five characters you noted. Repeat for each license shown.
After clearing old licenses, you can install fresh and activate with your new key. This manual license cleanup is particularly helpful when you need to uninstall Office completely before reinstalling with a new key but cannot use automated tools due to corporate policy restrictions.
Solution 4: Use the Windows Installer Cleanup for MSI-Based Office
Older Office versions (2010, 2013, and some 2016 editions) used MSI installers rather than Click-to-Run. These require a different cleanup approach.
Open PowerShell as Administrator.
List all installed MSI packages related to Office:
Get-WmiObject -Class Win32_Product | Where-Object {$_.Name -like "*Office*"} | Select-Object Name, IdentifyingNumberUninstall each package using its IdentifyingNumber (the GUID in curly braces):
msiexec /x {GUID-HERE} /qnWARNING: This removes products silently without confirmation. Double-check the GUID before running.
After removing all Office-related MSI packages, restart your computer.
How to Prevent This in the Future
Before upgrading Office versions, always uninstall the existing version completely rather than installing over it. The “upgrade” path sounds convenient but creates the exact conflicts we have been discussing.
Keep a copy of the Microsoft Office Removal Tool downloaded and saved. When you need to uninstall Office completely before reinstalling with a new key, having it ready saves time hunting for the correct download link.
Document your current product key before making changes. Use a key finder tool or check your Microsoft account at account.microsoft.com — you may need the old key if something goes wrong.
If you are purchasing new Microsoft Office licenses, verify the version matches your Windows edition. Office 2021 LTSC, for example, is not supported on Windows 10 Home. Mismatched versions cause activation headaches that look like incomplete uninstall problems.
Consider Microsoft 365 subscriptions for environments where you switch licenses frequently. The cloud-based licensing model handles key changes more gracefully than perpetual licenses.
Frequently Asked Questions
Why does Office say my product key is already in use after uninstalling?
This happens when licensing tokens remain in your AppData folder after a standard uninstall. The new Office installation reads these tokens and thinks the old license is still active. Running Microsoft’s Office Removal Tool clears these tokens completely.
Can I have two different Office versions installed at the same time?
Microsoft does not support running multiple Office versions simultaneously and strongly recommends against it. While technically possible in some configurations, doing so causes shared component conflicts, crashes in Outlook, and activation errors. Always uninstall Office completely before reinstalling with a new key or different version.
Will uninstalling Office delete my documents and emails?
No. Your Word documents, Excel spreadsheets, and Outlook emails stored locally (in PST files or cached from Exchange) remain intact. However, Outlook account configurations and custom signatures will need to be set up again. Export any custom templates before uninstalling.
How long does the Microsoft Office Removal Tool take to run?
The removal tool typically completes in 5-15 minutes depending on how many Office products are installed and your system speed. The mandatory restart afterward adds another 2-3 minutes. Budget about 20 minutes total to uninstall Office completely before reinstalling with a new key using this method.
Conclusion
Getting Office fully removed is more involved than most people expect, but the Microsoft Office Removal Tool handles the heavy lifting. When that is not enough, the manual cleanup commands give you complete control. Check out our Help Center for more activation guides if you run into trouble with your new installation.
Still stuck? Contact MCAKey support at https://mcakey.com/contact-us/ — we typically respond within a few hours.
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