What It Does
"Completely remove Outlook" doesn’t mean deleting one icon. It means: • Removing the Outlook desktop client binary (OUTLOOK.EXE) • Deleting its local data: PST/OST files, autocomplete cache (.NK2), and search index • Clearing the Outlook profile from Windows Credential Manager and the Registry • Disabling Outlook auto-launch behavior in Windows startup and file associations A real-world use case? A company laptop being reassigned to a new employee. IT needs to wipe all traces of the previous user’s email — including cached Exchange credentials, saved signatures, and offline mailbox copies — before handing it over. Just uninstalling won’t cut it.How to Set It Up
This isn’t a single-click process. It’s five coordinated steps — and skipping any one leaves residue. Step 1: Uninstall Outlook *via Office Deployment*Go to Settings > Apps > Installed apps. Find "Microsoft 365 Apps" (not "Outlook"). Click the three dots → Modify. Choose Quick Repair first — then Online Repair if that fails. If you need full removal, choose Uninstall here. This removes Outlook *and* preserves other Office apps only if you selected "Customize" during original install (rare). Most users installed the default bundle — so this removes Word, Excel, etc., too. Step 2: Delete Outlook Profiles
Press Win + R, type control.exe mlcfg32.cpl, and press Enter. This opens the Mail Setup dialog. Click Show Profiles → select each profile → Remove. Confirm every time. (This took me three days to figure out originally — the Control Panel Mail applet doesn’t appear unless you have at least one mail account configured.) Step 3: Wipe Local Data Folders
Delete these folders manually (paste each path into File Explorer):
%localappdata%\Microsoft\Outlook(contains OST, NK2, and log files)%appdata%\Microsoft\Outlook(signatures, templates, rules)%localappdata%\Microsoft\Office\16.0\Outlook\Offline Address Books(OAB cache — Outlook 365/2019 only)
Open Windows Credentials Manager (search in Start). Under Windows Credentials, scroll down and delete every entry starting with "MicrosoftOffice16" or "Exchange". Also check Generic Credentials for entries like "Outlook", "mscache", or "LiveID". Step 5: Reset File Associations
Go to Settings > Apps > Default apps > Choose default apps by file type. Scroll to
.msg, .pst, and .ost. Click each and set to "Look for an app in the Microsoft Store" — or leave blank. Don’t let them point to a missing Outlook.exe.
Configuration Options
Some settings control whether Outlook reinstalls itself or reappears after removal. Here’s what you actually control — and where:| Setting Name | Location | Options | Recommendation |
|---|---|---|---|
| Auto-reinstall via Microsoft Update | Group Policy or Intune (Admin-only) | Enabled / Disabled / Not configured | Disable if managing shared devices |
| Default mail app registration | Settings > Apps > Default apps > Email | Outlook / Mail app / None | Set to "None" to prevent auto-association |
| OST sync behavior | File > Account Settings > Account Settings > double-click account > More Settings > Advanced | Cached Exchange Mode on/off; Download shared folders | Turn OFF before removal — prevents ghost OST recreation |
| Startup folder scanning | HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Setup | ImportOldFiles DWORD: 0 or 1 | Set to 0 to stop Outlook from finding old PSTs on next launch |
| Search indexing inclusion | Indexing Options > Modify > uncheck Outlook folders | Checked / unchecked | Uncheck *before* removal — avoids lingering search errors |
| Add-in auto-load | File > Options > Add-ins > Manage COM Add-ins > Go | Each add-in has Load Behavior: Load on Startup / Load on Demand / Unloaded | Disable all before uninstall — prevents failed load attempts post-removal |
Real-World Examples
Example 1: Shared lab computers (University IT)At Tsinghua University’s engineering lab, 42 Windows PCs run Outlook for student email labs. After each semester, IT wipes Outlook but keeps Word/Excel. They use a PowerShell script that runs the five-step process above — plus deletes the Outlook registry key
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook — before pushing a clean image. Without Step 3 (deleting OST), students saw “mailbox unavailable” errors for 3 days after reassignment.
Example 2: Migrating from Exchange to Gmail (Small business)A Shanghai design studio moved 12 staff from Office 365 to Google Workspace. They didn’t just uninstall Outlook — they used Ctrl+Shift+Esc to open Task Manager, ended all Outlook processes, then ran outlook.exe /cleanprofiles before deletion. That cleared stale AutoDiscover XML caches that were redirecting Gmail setup to old Exchange servers. Example 3: Forensic cleanup (Legal compliance)
A law firm in Singapore needed to prove zero Outlook traces remained on a departing partner’s laptop. They used Process Monitor (Sysinternals) to log all Outlook-related file/registry access for 72 hours pre-removal — then repeated the scan post-cleanup. The only hits left were under
%windir%\System32\outlook.exe — which turned out to be a false positive (a legacy Windows component, not the Outlook client).
Limitations and Gotchas
You cannot fully remove Outlook from Microsoft 365 Apps without affecting other Office programs — unless you did a custom install (which < 7% of users do). Outlook 2016 and 2019 behave similarly, but Outlook 365 has tighter integration: its update engine may restore Outlook within 48 hours if Microsoft Update is enabled and the device is domain-joined. The Outlook Web App (OWA) remains accessible regardless — because it’s server-side. Removing the desktop client does nothing to webmail access, permissions, or mailbox retention policies. Cached Exchange Mode leaves OST files behind *even after profile removal*, unless you manually delete them (Step 3 above). And yes — that includes hidden OST files namedarchive_00000001.ost buried in subfolders.
One surprising tip: Outlook 365 stores autocomplete suggestions in %localappdata%\Microsoft\Outlook\RoamCache — not in the main Outlook folder. That folder survives standard cleanup. You must delete it separately.
Also: Outlook for Mac works differently. This walkthrough applies only to Windows desktop Outlook 2016, 2019, and Microsoft 365 Apps (v2308+). Outlook for Mac uses plist files and ~/Library/Group Containers — and requires different steps.
Finally, if your organization uses Microsoft Intune or Group Policy, admins can push Outlook back silently — even after you’ve deleted everything. Check with your IT team before assuming it’s gone for good.
Next Steps Checklist
Before you close this tab, verify these four items are done:- ✅ Ran control.exe mlcfg32.cpl and removed all profiles
- ✅ Deleted both
%localappdata%\Microsoft\Outlookand%appdata%\Microsoft\Outlook - ✅ Cleared credentials for "MicrosoftOffice16" and "Exchange" in Windows Credentials Manager
- ✅ Set
.msgfile association to "None" in Default Apps
