Other than change the limit of System Restore disk usage allocation to reduce allocation amount and free up the space, you can also immediately delete and reclaim almost all space used by System Restore and Shadow Copies (including Previous Versions) by using Disk Cleanup Manager to eliminate all but the most recent System Restore point.
To release the reclaim space used by System Restore, simply follow the steps:

1. Click Start button.
2. Type clean in the Start Search box.
3. Click Disk Cleanup from the search results list.
4. Select Files from All Users on this computer option.
5. Click OK on Disk Space Cleanup Manager for Windows User Access Control permission request dialog.
6. Choose a drive letter from the drop down list, and press OK.
7. Disk Cleanup will perform calculation to determine how much space it can free. Once done, click on More Options tab.

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