deleting unused WoW files

[EaTCarbS]

You won't be able to make the WoW directory much smaller than you have it now.

[MiRai]

The cache folder has been there as long as I can remember it. It makes it easier for your system to "fetch" whatever has
been stored in there. You can delete it all you want and it will continue to come back everytime you play the game and it
will get loaded with things that you've seen in that session. People do delete their cache folders every once-in-a-while
because it is one of the first basic troubleshooting steps that Blizzard has you do in the event of an error:

Delete your Cache, Interface, and WTF folders

You won't be able to make the WoW directory much smaller than you have it now.

This ^