Hi Codee,
Without examining the site directly it's difficult to say that the files are 100% safe to delete, but I can say that I've never come across an issue caused by someone clearing their temp folder. The most common use for this folder is to temporarily store files as they're being uploaded or created, however, sometimes the "cleanup" process is interrupted or prevented for some reason, and the temporary file is not deleted automatically.
Can you tell me a few example filenames that are in your temp folder? If they end in ".tmp" then they are genuine temp files and can be deleted.
Thanks,
Daniel
Technical Lead
interactivetools.com