It is likely that your C drive is so full because you have a lot of files and programs stored on it. To help free up space on your C drive, you can try the following steps:
1. Uninstall any programs you are no longer using.
2. Move large files to an external storage device or another drive.
3. Delete any temporary files or files you no longer need.
4. Use Disk Cleanup to remove unnecessary system files.
5. Adjust your System Restore settings.
If these steps do not help you free up the necessary space on your C drive, you may need to consider replacing your hard drive with a larger capacity model.