Uninstall Outlook 365 & Reinstall Safely: Windows Steps

Yes, you can uninstall Outlook 365 and reinstall it on Windows safely, as long as you follow the correct steps to preserve your data and avoid activation issues. This guide walks you through the full process, from backing up your emails to reinstalling the app and troubleshooting common problems.

Why You Might Need to Uninstall and Reinstall Outlook 365

Outlook 365 (part of Microsoft 365) can develop issues that a simple restart or repair won’t fix. Common reasons for a full uninstall/reinstall cycle include:

• Persistent crashes or freezes that occur even after updating Windows and Office.
• Corrupted profile or data files that cause sync errors, missing emails, or repeated password prompts.
• Add-in conflicts that prevent Outlook from starting normally.
• Incomplete Office updates that leave the installation in an unstable state.
• Switching from a 32-bit to a 64-bit version (or vice versa) to match your system or other Office apps.

Before doing anything, know that uninstalling Outlook 365 does not delete your emails, contacts, or calendar items if you use an Exchange, Microsoft 365, or IMAP account – those are stored on the server. However, if you use a POP3 account, your emails are stored locally on your PC, so a backup is essential.

Step 1: Back Up Your Outlook Data (Crucial for POP3 and Local Archives)

Even if you think everything is on the server, it’s safer to export your data to a .pst file. This covers POP3 accounts, local folders, and any archived items.

1. Open Outlook and click File > Open & Export > Import/Export.
2. Choose Export to a file and click Next.
3. Select Outlook Data File (.pst) and click Next.
4. Choose the folders you want to back up (usually your entire mailbox) and check Include subfolders.
5. Click Finish and save the .pst file to a safe location (e.g., an external drive or OneDrive folder).

Also note your email account settings (incoming/outgoing server names, port numbers, and encryption methods) – you’ll need these when re-adding the account. You can find them under File > Account Settings > Account Settings > select the account > Change.

Step 2: Uninstall Outlook 365 (Not Just the App)

Outlook 365 is part of the Microsoft 365 suite, so you can’t uninstall it as a standalone app in most cases. You need to remove the entire Office installation.

1. Press Windows + I to open Settings.
2. Go to Apps > Installed apps (or Apps & features on older Windows).
3. Scroll to Microsoft 365 or Microsoft Office (the entry may say “Microsoft 365 Apps for enterprise” or “Microsoft Office 365”).
4. Click the three-dot menu (or select it) and choose Uninstall.
5. Follow the prompts. Windows may ask for confirmation; allow the process to complete.

If you only see an “Outlook” entry, that’s a separate app from the Microsoft Store (the new Outlook for Windows). Uninstalling that won’t affect the classic Outlook 365. For classic Outlook, you must uninstall the whole Office suite.

Step 3: Clean Up Leftover Files and Registry Entries (Optional but Recommended)

After uninstalling, some files and registry keys may remain. These can cause issues during reinstallation. Use the official Microsoft Support and Recovery Assistant (SaRA) tool to fully remove Office. Download it from Microsoft’s official site, run it, and choose “Office” > “I’m having problems installing Office” – it will guide you through a clean removal.

If you prefer manual cleanup (only for advanced users):

• Delete the %LocalAppData%\Microsoft\Outlook folder (but you already backed up your .pst, right?).
• Delete the %AppData%\Microsoft\Outlook folder for settings.
• Open Registry Editor (regedit) and delete HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook – but only if you’re comfortable editing the registry. A mistake can break other apps.

Most users can skip manual registry editing and rely on SaRA.

Step 4: Reinstall Outlook 365

Once uninstalled, reinstall Microsoft 365 (which includes Outlook).

1. Go to office.com and sign in with the Microsoft account associated with your Microsoft 365 subscription.
2. Click Install apps (usually top-right) and select Microsoft 365 apps.
3. Download the installer and run it. It will install the entire suite, including Outlook.
4. Follow the on-screen instructions. You may be asked to sign in to activate.

If you have a volume license or a work/school account, you might need to install from your organization’s portal instead.

Step 5: Re-Add Your Email Account and Restore Data

After reinstalling, launch Outlook. It will ask you to set up an account.

1. Enter your email address and click Connect. Outlook will try to auto-detect settings.
2. If auto-detection fails, use the manual settings you noted earlier (server names, ports, etc.).
3. Once your account is set up, if you have a .pst backup, go to File > Open & Export > Import/Export > Import from another program or file > Outlook Data File (.pst) and select your backup.

Your emails, contacts, and calendar should now be visible.

Frequently Asked Questions

Will I lose my emails if I uninstall Outlook 365?

Not if your account is Exchange, Microsoft 365, or IMAP – emails are on the server and will reappear after you re-add the account. For POP3 accounts, emails are stored locally, so you must export a .pst file before uninstalling to avoid losing them.

Can I uninstall just Outlook without uninstalling the whole Office suite?

No, classic Outlook 365 is part of the Microsoft 365 suite and cannot be removed individually via the standard uninstall process. You must uninstall the entire suite and then reinstall it. The new Outlook for Windows (a separate app) can be uninstalled independently from the Microsoft Store.

Why does Outlook keep asking for my password after reinstall?

This usually happens because Windows Credential Manager still has old credentials. Open Control Panel > Credential Manager > Windows Credentials, and remove any entries under “Generic Credentials” that mention Outlook or Microsoft Office. Then restart Outlook and re-enter your password.

Is it better to repair Office instead of uninstalling?

Often yes. Try a Quick Repair first: go to Settings > Apps > Installed apps, select Microsoft 365, click Modify, and choose Quick Repair. If that doesn’t fix the issue, try Online Repair (which takes longer but is more thorough) before resorting to a full uninstall/reinstall.

How long does the uninstall/reinstall process take?

Uninstalling takes about 5–10 minutes. Downloading and reinstalling Microsoft 365 can take 15–30 minutes depending on your internet speed. Setting up your account and importing data adds another 10–20 minutes. In total, plan for about an hour.

Will my Outlook settings (signature, rules, etc.) be preserved?

Most settings like signatures and rules are stored in your mailbox or in the Outlook profile. If you use a Microsoft 365 or Exchange account, many settings sync. For local settings, they are stored in the registry and will be lost after uninstall. You can export your signatures manually by copying the files from %AppData%\Microsoft\Signatures before uninstalling.

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