On my Windows 8.1 laptop with a small SSD (100GB), disk space was running out. When I checked disk usage by folder using TreeSize, I found that C:\Windows\Installer was taking up over 22GB! A quick online research revealed that I couldn’t delete files from this folder safely. However, I also learned that it could be holding files that were no longer in use or needed.
On further search, I found this neat little utility called Patch Cleaner, which looks for such unused files and gives you the option to delete them or back them up to another location. When I ran it, I found that about 15GB out of those 22 were being hogged by the files that were no longer needed! All of these 400+ unused files are MSP files. I have moved these files to an external hard disk just in case there is an issue later. Restoring the files is as easy as copying them back to the installer folder.
Thank you Patch Cleaner for freeing up over 15% of my disk space!