Duncan,

I use Clear Selected to remove a grib file from the inventory of files that can be used for routing. The cleared files are retained in the Grib folder where they can then be individually deleted or removed to another event-specific folder for future analysis.

In the grib folder the files are deleted by selecting/ highlighting and walking the delete key on my keyboard.

I guess the short answer to your question is that permanent deleting is accomplished in the grib folder and not in the Weather file panel.

I access the grib folder through the Weather file panel or else through the Program Data folder.

Hope this helps.