Inside of your Windows folder you will notice multiple folders named “$NtServicePackUninstall$” or similar. Because these folders are hidden by default, you may have to go into My Computer or Windows Explorer and select Tools, Folder Options. Select the View tab and change the Hidden Files and Folders setting to Show Hidden Files and Folders. These folders contain the uninstall information for any Windows updates you have applied.
If you ever wanted to remove an update (which can be done with Windows’ Add/Remove Programs feature), these folders would be used. However, if you don’t plan to uninstall any updates (99% of the time you never will need to), you can recover some disk space by removing those folders. You can delete any of the folders that start and end with a “$”, except for “$hf_mig$” . Depending on the number of updates you have installed, deleting these folders can save between one and several hundred megabytes worth of space.
$NtUninstallKB, $NtUninstall, $NtUninstall$, $NtUninstallKB$