Method 1: (suitable for friends whose computers have just been upgraded to WIN 10)
First, open "this computer" on the desktop.
Next, locate drive C, right-click and select Properties, and then click Disk Cleanup.
Finally, click Clean System Files. The newly upgraded WIN 10 will have a Windows.old file, put a tick in front of it, and then click OK.
Method 2: (This is the download computer housekeeper)
1. Open the computer housekeeper and find "System Disk Slimming". After the tool installation is completed, click "Start Scanning".
2. Check what you need, and then click "Publish Now".
3. Then find "software to move".
4. Open it, select drive C, click "Installed Software", modify the file path, and click "Start Moving".
This is the way to solve the problem of full C disk ~ ~ ~