Windows 10 Migration Guide: Storage Clean-Up And Optimization
The ability to fully roll back to your Windows 7 or 8.1 installation within 30 days is a very easily overlooked feature of the Windows 10 upgrade process. The feature is a lifesaver if you encounter issues, such as missing or incompatible drivers, and need to quickly recover without needing to start from scratch. This ability doesn't come without consequences, though. In order to offer this feature, Windows 10 is essentially keeping another completely separate Windows installation on your PC. Windows will attempt to automatically clean up these files after 30 days, but some users have reported that remnants still get left behind so double checking is encouraged. Instead of waiting all that time and trusting it just happens, however, there is a quick and simple process to nip it in the bud yourself once you've determined that you are sticking with Windows 10 and everything is compatible.
These files are scattered throughout your system and include a number of hidden directories, with the bulk of them located in Windows.old and the hidden $Windows.~BT and $Windows.~WS directories.
You've stayed your welcome
Simply deleting these directories will not result in a perfect cleanup. However, the process to nuke them is fairly straightforward and may be familiar to anyone who has performed any other Windows upgrade install. The first thing to do is locate the Windows.old folder on the system drive and pick through it for documents and any other files that need to be recovered. All your files should have been migrated automatically in the upgrade process but it never hurts to be thorough. Anything of interest should be within the Windows.old\Users path and can be moved to its respective directory in the system Users folder. Both of these directories should be located in your root directory, likely on your C: volume. Your mileage, of course, may vary. Do not delete Windows.old just yet, but know that anything left in it will be wiped shortly.
With your files squared away, proceed to the Disk Cleanup tool by typing "disk cleanup" into the search box or by browsing to All App/Windows Administrative Tools/Disk Cleanup from the Windows Start menu.
Also acceptable: Free up disk space by deleting unnecessary files. Why not?
Once the initial scan of your files completes, click the button to Clean Up System Files.
It's as if the the button was labelled!
After a second scan there will be additional options exposed. You should select "Windows upgrade log files," "Previous Windows installation(s)," and "Temporary Windows installation files."
You may choose to also keep the default options or add and remove other options. With the suggested three options selected, the total amount of disk space to recover should exceed 10GB and will often be significantly greater. Disk Cleanup promises here to restore nearly 35GB even on my seldom used laptop. Click OK and watch all the junk get scrubbed away, freeing up your precious storage for better use.
Every little bit helps!
Enjoy your new cleaned-up and tuned-up OS file system. Pour yourself a cold beverage of your choice. You've earned it.