How to Delete Old Windows Files Easily & Securely?

Can I delete old Windows files?

Some users find their computers become quite slow and the free space on the C drive is suddenly smaller after an update. How does this happen?

▶ Old Windows files
If you check your C drive immediately after a system update, this is probably caused by the old Windows files of the previous version. All relevant files are stored in a folder called “Windows.old”. The Windows.old folder may need almost 20GB which holds all of your prior Windows installation's files and data, such as Windows system files, user account settings, User Profile, User Folder files, and so on.
If you don't like the new version, you can use it to restore Windows to a prior version. You may also search the Windows.old folder for a specific file that was not correctly migrated to your fresh Windows installation.

▶ Is it safe to delete old Windows files?
Normally, your Windows will clean up this folder after 10 days. But if you need available space in a rush, or you’re sure you won’t go back to the previous version, you can manually delete those old Windows files manually. It’s safe.

Why can’t you delete old Windows files?

Since all related files are in one folder, you can easily delete the whole folder to remove all related files. However, some users are not allowed to remove it, and many of them see the report showing the file not found or the target is not a valid file or directory.

This situation might be caused by the following reasons:

◤ The related files are deleted by the system
Different systems have a different time to delete old Windows files.
Windows 7 and older OS, those files will be removed automatically in 30 days after the OS update; Windows 8.1/8, after 28 days; Windows 10, after 10 days.

◤ You don’t have administrator permission
Windows.old folder requires administrator permission from the system to make changes to this folder.

How to delete old Windows files?

In this part, we’ll show you three ways to delete old Windows files.

But first, we need to switch your account to the administrator. If you have several user accounts on the PC, switch to the administrator account as follows:

Step 1. Open the Windows start menu from the bottom left and select your username

Step 2. Hit "Administrator" on the list.

Way 1. Delete old Windows files via Disk Cleanup

Step 1. Type “disk cleanup” in the Windows search box, then select Disk Cleanup in the search results.

Step 2. In the pop-out window, select C: to clean up and click “OK”.

Step 3. Wait till the Disk Cleanup for (C :) are open. Then click the "Clean up system files" option.

Step 3. Scroll through the list of folders and select “Previous Windows installation(s)” and click “OK”.

Way 2. Remove old Windows files with Storage settings

Step 1. Open your Windows Settings and click Settings

Step 2. Click Storage. Windows will take a few moments to analyze your disks and display how you're utilizing your disk space.

Step 3. Click Temporary Files.

Step 4. Check the box next to "Previous version of Windows." If you've recently upgraded, you'll see this option in the list.

Step 5. Click Remove files above the list. A confirmation pop-up will appear.

Step 6. Click Continue to confirm. This removes all selected files, including Windows.old folder that contains your previous version of Windows.

Way 3. Use CMD to clear old Windows files

Step 1. 1. In the search box next to the start button, type “cmd” and select "Run as administrator".

Step 2. In the popup window, type the following 3 lines and hit "ENTER" after each of them:

• takeown /F c:\Windows.old\* /R /A /D Y (If the Windows.old folder is not on the C drive, replace C: with the correct drive letter.)

• cacls c:\Windows.old\*.* /T /grant administrators:F
• rmdir /S /Q c:\Windows.old

How to delete large old files in Windows?

After deleting the old Windows folder, your C drive may release almost 15GB-20GB of free space.

In fact, there are many old large files like old Windows files on your disk but the sad thing is that it’s impossible to manually find them all and remove them. Thus, if you want to further clean up invalid large files to keep your system and disks in a nice status, then we suggest you use professional cleaning tools. Here, we recommend you AOMEI Partition Assistant Professional, a disk and partition manager for Windows 11/10/8/8.1/7/XP.

This tool has a “Delete Large Files” feature to scan the selected space and filter the large files, and some of them will be marked in red to remind you to cautiously delete (you still can delete them according to your exact needs).

Step 1. Install and launch AOMEI Partition Assistant, then click "Free up" and "Delete Large Files".

Step 2. In the pop-up window, select the partitions that you want to find large files, and click "Start Scan" to scan for large files.

Step 3. When the scan is complete, all large files found are listed. Tick the files you want to delete, and then click the "Delete" button. You can also delete files marked in red if you’re sure they won’t hurt any programs or your system.

Step 4. This step will list all the files you have ticked to delete, click "Delete Now" after confirming that it is correct, then these files will be deleted successfully.

To sum up

If you don’t know how to delete old Windows files, then this post will help you a lot. You can try the above 3 ways to delete Windows.old files, and if you need, you can use AOMEI Partition Assistant to deeply clean your disks.

What’s more, this tool also has the features like “App Mover”, “Merge Partitions”, and “Allocate Free Space” to help you release more free space on the C drive. And it can also clone disks, migrate OS, convert a disk to MBR/GPT without deleting partitions…

In addition, you can choose the Server Edition if you’re using Windows Server 2025/2022/2019/2016/2012(R2)/2008(R2)/2003 system.