I’m not 100% sure of anything that you can delete, but if there are any leftover tgz files from the NR download I believe you can delete those.
it is unfortunate that it takes up so much space, but i believe the next generation of fragment picking will take up signifigantly less space.
http://robetta.bakerlab.org/fragmentsubmit.jsp
is where you can ask the bakerlab’s server to make fragments for you, if you have disk space issues.