The following script (from MSDN - slightly modified) can be used to clear the System Restore points quickly. It automatically disables System Restore, clears all the Restore points and re-enables System Restore on all drives. Copy the following script to a notepad and save as "ResetSR.VBS".
strComputer = "."
The above is an equivalent of selecting Turn Off System Restore on all drives (which clears all the Restore points) and the last line in the script re-enables the System Restore points.
Related: Print the list of all available System Restore points to a file