How do I delete unused resources from a Storyline 360 file.

I have a large Storyline file that will not upload to the Review site.  I have checked my internet, rebooted my router, along with several other attempts.  I know there is a way to delete unused resources within a storyline file but I cannot find how to do it.  Can someone help me with the steps in do this?

 Thank you,

Barbie