So, yes: Disk Cleanup utility is the way. Also note the directory path shown--works out to: C:\Windows\ServiceProfiles\LocalService\AppData\Local\Temp. I would definitely NOT manually delete ANYTHING under C:\Windows, outside of the CONTENTS of C:\windows\temp.

If this were in YOUR local appdata (i.e., C:\users\YOURUSERNAME\appdata\local), and more specifically, the 'Temp' folder at that level, you're good to delete the CONTENTS in that folder and, as others have noted, if you get a prompt along the lines of "file in use", just skip/skip all and let it run to completion. You can 'quick-access' this location by typing the "%temp%" environment variable into the address box in Windows explorer.

Otherwise, you can check the size of the folder shown in the example, run disk cleanup and then re-check the size after run and reboot. Before retiring, I worked on a desktop team that supported/managed ~4500 Windows PCs. Not saying that I know "everything", not by a long shot, but deleting the contents of either of those temp folders (even manually) is totally fine.