When you upgrade your existing Windows 7 or Windows 8 or Windows 8.1 computer to Windows 10, you might see that you ‘lost’ some disk space. In my case, my laptop has an SSD and space is limited.

What happened is: Microsoft kept my old operating system so I could revert back to it if I didn’t like Windows 10. That’s pretty convenient for them to build Windows 10 like that, but if you don’t plan on going back to a lower Windows version, that old OS is taking up space on your hard drive and you want to get that back.

To do so, open your shiny new start menu on your Windows 10 installation and type in disk. Windows will now list all of your apps, settings and files which have the word ‘disk’ in them. Find the option Free up disk space by deleting unnecessary files.

Free up disk space by deleting unnecessary files

This will open up the Disk Cleanup tool. It will automatically start checking your system for unnecessary files it can remove. Once it’s finished, however, you first want to click on Clean up system files in the bottom left corner. The same window will open again, but this time, the Disk Cleanup will also check your system files for items it can purge.

Disk clean up results. Check all the boxes.

Now, you want to check all the boxes. You will most likely see that Previous Windows installation(s) and Temporary Windows installations files will take up a few GB (GigaBytes) each! Click OK to confirm you want to delete these files.

Restore previous Windows installation warning

Heads up! Windows will however warn you that, by deleting these files, you can no longer downgrade back to Windows 7 or 8(.1). If you plan to downgrade in the near future, you can still cancel this operation. Otherwise, you ahead and dismiss the warning.

That’s it, you successfully regained at least a few GB’s!

Increased amount of free disk space after Disk Cleanup