You can use Disk Cleanup to delete restore points and free hard disk space on your computer.
Disk Cleanup deletes all but the most recent restore point on your computer. In some editions of Windows Vista, restore points can include previous versions of files. Those previous versions will also be deleted.
Open Disk Cleanup by clicking the Start button , clicking All Programs, clicking Accessories, clicking System Tools, and then clicking Disk Cleanup.
In the Disk Cleanup Options dialog box, click Files from all users on this computer.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
If prompted, select the drive that you want to clean up, and then click OK.
Click the More Options tab.
Under System Restore and Shadow Copies, click Clean up, and then, in the confirmation dialog box, click Delete.
To continue using Disk Cleanup for other drives on your computer, click the Disk Cleanup tab. To quit Disk Cleanup, click Cancel.