Published Apr 26, 2026, 11:01 AM EDT
Oluwademilade is a tech enthusiast with over five years of writing experience. He joined the MUO team in 2022 and covers various topics, including consumer tech, iOS, Android, artificial intelligence, hardware, software, and cybersecurity. In addition to writing at MUO, his work has appeared on HowtoGeek, Cryptoknowmics, TechNerdiness, and SlashGear.
Oluwademilade attended the University of Ibadan in Nigeria, earning a medical degree from the College of Medicine. Excelling in public service, Oluwademilade was honored with the title of Global Action Ambassador by a student organization affiliated with the United Nations. He received this designation in Kuala Lumpur, Malaysia, in recognition of his efforts to make a positive global impact in 2020
In his free time, Oluwademilade enjoys testing new AI apps and features, troubleshooting tech problems for family and friends, learning new coding languages, and traveling to new places whenever possible.
I have a bad habit of stockpiling open source installers and poking around with obscure registry tweaks to squeeze a bit more out of my system. It adds up fast. My storage drive usually takes the hit, and my main partition has been flirting with full capacity for months. I keep looking for a clean, reliable way to deep clean my Windows PC without resorting to questionable third-party tools.
It was only when I was idly poking around the Disk Cleanup window one day that I spotted something I had walked right past a dozen times before: Clean up system files.
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The standard scan is basically just dusting
Disk Cleanup is one of those tools that has been baked into Windows for so long it practically blends into the wallpaper. Most people who know about it open it, check a few boxes, hit OK, and move on with their lives. But running Disk Cleanup in its default state is essentially asking a librarian to tidy up only the front desk, leaving the entire stockroom untouched.
The standard scan looks at things like your Recycle Bin, temporary files, cached thumbnails, and a handful of other surface-level categories. These are useful, but they tend to hold relatively modest amounts of data. The real weight lies elsewhere, in parts of the system that the regular scan lacks the permission level to access.
That is where "Clean up system files" comes in.
One click, and the gloves come off
Going from light sweeping to deep-core excavation
Here’s how to go through it from scratch. Open the Start menu, type “Disk Cleanup” into the search bar, and click the result that shows up. There are a few different ways to launch it, but this is the most straightforward.
Depending on your system setup, Windows may ask you to choose a drive first or skip straight to scanning. Either way, let it run. Within a minute or so, you will land on a window showing a list of file categories and a combined total at the top. That total is what the regular scan found. Note the number, but do not delete anything yet.
Now look toward the bottom-left of that same window for the "Clean up system files" button. Click it. Again, Windows may prompt you to confirm a drive, or it may go straight into rescanning, depending on your configuration. This second scan takes noticeably longer than the first because it is working through deeper layers of your installation.
When it finishes, you will be back at a window that looks nearly identical to the one before, with one key difference: the total will very likely be a completely different number, and the category list will have grown. In my case, the regular scan surfaced 2.77 GB. After clicking "Clean up system files," that figure jumped to 5.11 GB, and an entirely new category appeared at the top of the list that had been completely invisible before. The elevated scan also dug deeper into categories that were already showing up, with Temporary files alone climbing from 2.00 GB to 3.18 GB once Windows had the permissions to count them properly. This is the version of Disk Cleanup that most people never see. Now you can start making considered choices about what goes.
Not every checkbox deserves a checkmark
Tread lightly around the ghosts of Windows past
The extended list that appears after the elevated scan includes categories that the basic version never shows you. Some are straightforward wins. Others deserve a moment of thought before you tick the box.
Windows Update Cleanup is typically the most significant addition, and in my case, it was sitting at 1.11 GB on its own, not included in the regular scan. When Windows installs updates, it keeps older versions of system files around so that you could theoretically uninstall a problematic update later. On a machine that has been receiving cumulative updates for a long time, this category can grow considerably. It is safe to clear in most cases, particularly once you are confident that a recent update has been stable on your machine for a few weeks.
Delivery Optimization Files and DirectX Shader Cache are also safe to remove without hesitation. Delivery Optimization Files are leftovers from Windows' peer-to-peer update distribution system. The DirectX Shader Cache is compiled graphics data that games and applications generate to run faster. Still, applications will rebuild it the next time they run, so clearing it costs you nothing in the long run.
If you are still in the first few weeks after a major upgrade and have any lingering doubts about stability, hold off a little longer.
The category that warrants the most careful thought is "Previous Windows installation(s)," if it appears on your machine. This is your Windows.old folder, the full backup of your prior installation that lets you roll back if something goes wrong after an upgrade. It can occupy a significant amount of space, and deleting it is an action that cannot be undone. If your system has been running well since the upgrade, and you have no plans to revert, removing it is a perfectly reasonable call. If you are still in the first few weeks after a major upgrade and have any lingering doubts about stability, hold off a little longer.
There are also options to remove system restore points and volume shadow copies, though Microsoft does not recommend this unless you have a specific reason. These serve as recovery checkpoints and are worth keeping unless storage is critically tight and your system is otherwise in good health.
Once you have selected the categories you are comfortable removing, click OK, confirm the deletion when prompted, and let the tool work through the list. The process can take several minutes, depending on the volume of files being cleared. When it finishes, the space is yours again.
Respect your elders, especially the ones that free up 5GB
Windows has shipped Disk Cleanup since the late 1990s, and as of this writing, Microsoft has not marked it as deprecated, even though newer alternatives like Storage Sense are now available in Settings. That makes it worth knowing well, not just as something you reach for when a low-storage alert forces your hand, but as a tool you run intentionally every few months, before things get desperate enough to matter. The button was always sitting right there in the corner, doing its best to pass as furniture. Hopefully, now you know exactly what it can do.