Yes, you can delete C:\Windows\WinSxS\Temp
Windows Update on Windows 10 taking hours to install updates? TiWorker.exe sitting at 100% CPU use? You aren't alone. For whatever reason, TiWorker (Trusted Installer Worker) spends the majority of its time opening and closing millions of file handles to empty directories in C:\Windows\WinSxS\Temp\InFlight (accidentally quadratic?). Searching around the internet you'll find plenty of people advising caution and never deleting things in the WinSxS folder (and for good reason), however this is very clearly a temp directory and should be fine to delete. I did exactly that, and my cumulative update that previously took over an hour to reach 77% (on a 7950X!) installed entirely in 3 minutes.
Anyway, if you want to do this safely, make sure there are no updates currently being installed. Pause updates in control panel, then reboot just to be safe. Stop the Winows Update service, then use PsExec or your favorite tool to become SYSTEM and nuke the C:\Windows\WinSxS\Temp\InFlight folder. Reboot, then check for updates again and they should install much faster.
Do this at your own risk.