No, it isn't backup file.
I looked into this problem a bit, really, Windows makes sometimes such a temporay files during upgrading. This file is used only once.
File size may be deceiving, but for Windows it is what you wrote - 600GB. This is because apart the use of data Windows is not a file re-indexed or registered.
Your only normal activity is - to destroy the file.
If you have a HDD hard drive, it is advisable to wipe it (takes very long time, even if to select overwrite once with random data) or simply delete it. Then You can at every time wipe free space.
If You have an SSD, then is possible only simply delete (no wipe never) and if done, run "Trim" C drive. Thats all. All other will be done automaticly by system.
If You have some problems, ask, maybe I can help You.