Remove Windows.old Folder: Freeing Up Space After an Upgrade

After upgrading to a new version of Windows 10, you’ll often find a Windows.old folder sitting in the root of your C: drive — it holds your previous installation so you can roll back if needed, but it can be several gigabytes and isn’t needed once you’re confident the upgrade went smoothly.

Removing It (Disk Cleanup)

1. Right-click the Start button and open Run (or press Win+R), then type cleanmgr and press Enter.
2. Select your C: drive if prompted.
3. Click Clean up system files (this second, elevated scan is what actually shows the Windows.old option).
4. Tick Previous Windows installation(s) along with anything else you want to clear, then click OK and confirm.

Modern Alternative

On current Windows 10/11 builds, you can also do this through Settings > System > Storage > Temporary files, which lists “Previous Windows installation(s)” alongside other reclaimable space without needing the older Disk Cleanup tool at all. Note that Windows.old is only kept for a limited time (typically around 10 days) before Windows removes it automatically anyway, so there’s no harm in leaving it if you’re not in a hurry to reclaim the space.

Screenshot: Disk Cleanup with Previous Windows Installation(s)

Still the Same Process in 2026 (Updated for 2026)

Both methods above still work unchanged on current Windows 10 (including ESU-enrolled machines past the 14 Oct 2025 end-of-support date) and Windows 11 — the Disk Cleanup “Previous Windows installation(s)” option and the Settings > System > Storage > Temporary files equivalent both remain in place, and Windows.old still self-deletes automatically after roughly 10 days if you don’t clear it manually. One thing worth knowing if you’re planning a bulk cleanup across many machines: cleanmgr /sageset:1 followed by cleanmgr /sagerun:1 lets you preconfigure and script the cleanup categories (including Windows.old) rather than clicking through the dialog on every machine individually.