I know this is old, but just had to deal with this for an upgrade.  The syntax for deleting a file from that directory is:filesys delete /nxos/tmp/<filename>

ES 86 is now avaialable on the downloads page.  Apparently 85 had an issue with corrupting Exchange search folders according to the release notes.

ES 85 is now on the downloads page.

It appears that the latest ES available for Unity 5.x is ES 83, but 85 is required for Exchange 2010 compatibility.  Is ES 85 making its way to the download site or am I missing something?