I’m guessing you’re showing hidden files, folders and drives but you are hiding protected operating system files.
I don’t know that you can get rid of much in that folder, but this is what I suggest to clean up disk space:
You do have a substantial amount of data there. I’d recommend you do two things…
1) Perform another Disk Cleanup, this time click on Clean Up System Files, click on the More Options tab, click on the System Restore and Shadow Copies Clean up button, select Delete, Okay, and Delete.
2) The only cleaner I’ve used which cleans up temporary files very well is Auslogic Speed Boost. It’s a free download and the temp file cleanup is also free. There are other features which must be paid for but I’m not recommending that. Just download the software, install it (read everything as you install, say no if you do not agree). Run the application and tell it to recover your temp space. After that you can stop the program from running (it likes to run in background and will be on the task bar) and it will be there the next time you feel the urge to purge.