In fact, when installing the system without deleting the data of drive C, if it is reinstalled, the previous system will be placed in the old Windows folder. See if there is such a folder. If yes, you can do the following:

1, win+r, in operation, input: msconfig,

2. Select Boot in the pop-up interface, first set the system you want to use as the default, and then delete another one.

3. Right-click disk C-Properties.

4. Select "Disk Cleaning" in the pop-up interface.

5. After the automatic scanning of the system is completed, click Clean System Files in the interface.

6. At this time, the system will scan it again. After scanning, the window above will pop up. There will be more options for system files, and the size will be at least several hundred megabytes.

7. At this time, check the options that occupy more space, and click OK, and the system will automatically delete them.

8. After the above, two things will be accomplished:

(1) Delete redundant systems.

(2) After cleaning disk C, the space will become larger.

9. You can also click on the tools above in the properties window of drive C and select defragmentation, which will also make more space.