1. It is suggested to try to use optimization software such as window optimization master, Master Lu and Super Rabbit. Delete all files left by patching in the folder with "$" under C:\WINDOWS\. It should be noted that these folders are hidden properties. If it is deleted, the patch cannot be deleted normally in the future, because these files are system patch backups.

2. It is suggested to check the folder C:\Program Files to see if there is any non-system software installed here. If yes, first copy the folder where these softwares are located to drive D or other drive letters, then delete the softwares in Add and Remove Programs, and finally reinstall the softwares, and choose the path of the just copied drive D or other drive letters, which means that cover the installation has done it once and the files will not be lost.

3. Check whether your system has System Restore turned on. Turning off this feature can expand some available space.

4. See if you have turned on the hibernation function. Turning off this feature can also expand some available space.

5. click start->; Program-> Attachment-> System tools-> Disk cleaning. Clean disk C.

6. Delete all files in the system TEMP folder, and delete IE temporary files.

7. If your C drive uses FAT32 format, it is recommended to use NTF format. After use, you can right-click the properties of disk C and select "Compress this disk to save disk space".

I think you can satisfy my answer! It can also bring you some help.