There is nothing more frustrating than trying to install a new game or update Windows, only to be hit with the dreaded "Low Disk Space" error.

Most people resort to manually hunting through their folders, deleting old downloads, and emptying the Recycle Bin. But even after all that work, the C: drive is still full. Why? Because Windows hides massive chunks of temporary files, old update caches, and system logs that you can't easily see.

Fortunately, Windows has a built-in, professional-grade cleanup tool that runs directly from the Command Prompt. Here is exactly how to use the "SageSet" command to force Windows to deep-clean your drive.

Step 1: Open Command Prompt as Administrator

To give the command permission to delete system-level junk files, you must run it with Administrator privileges.

  1. Click the Start menu.
  2. Type cmd.
  3. Right-click on Command Prompt and select Run as administrator.

Step 2: The Secret Advanced Cleanup Command

Most people know about the standard Disk Cleanup tool (cleanmgr), but they don't know about the hidden switch that unlocks dozens of extra cleaning options.

In your Command Prompt, type this exact command and press Enter:

bash

cleanmgr /sageset:1

What just happened?

A window will pop up called "Disk Cleanup Settings." Because of the /sageset:1 switch, this window has unlocked every single hidden cleanup option in Windows.

Scroll through the list and check every box you want Windows to clean. This includes:

  • Delivery Optimization Files (huge temp files from Windows updates)
  • Device Driver Packages (old drivers taking up space)
  • Windows Error Reporting Files
  • Old ChkDsk files
  • Previous Windows installations (can be 10+ GB)

Click OK to save these settings.

Step 3: Execute the Deep Clean

Now that you have told Windows what to clean, you need to tell it to actually do it.

In the same Command Prompt window, type this command and press Enter:

bash

cleanmgr /sagerun:1

You will see a progress bar appear as Windows aggressively deletes gigabytes of invisible junk from your system. Depending on how long it's been since your last cleanup, this can free up anywhere from 2 GB to 20 GB of space in just a few minutes.

🔥 Bonus Command: Clean Windows Update Leftovers

If you are still starving for storage space, Windows Update leaves behind a massive cache of old installation files. You can force Windows to purge them by running this command:

bash

dism /online /cleanup-image /startcomponentcleanup

(This will take a few minutes to complete. Once it finishes, you will often see another 3–5 GB of space reclaimed).

What to do next?

Freeing up disk space is step one for a fast PC. If your storage is finally clean but your computer is still running slow, you need to find out what is using all your memory.

Read our guide on The Secret Windows Command to Instantly Find What is Eating Your RAM to instantly identify and kill the background apps dragging your PC down.

And if you want to ensure your newly cleaned drive is running at maximum speed, run The Secret Windows Refresh Command to Instantly Speed Up Your SSD.