Deleting all traces of appended file..?

This is probably a quickly-answered question, but I just can’t find an answer anywhere, after searching.

At some point I must have accidentally appended a copy of my original .blend into the original, and now I’m stuck with it’s presence in the Outliner panel, and though I’ve deleted most of it’s tangible elements, it’s still listed. For the sake of cleaning up and not having anything of the appended copy doubling up on processing time… how do I delete the appended file from the original? I can’t find any means to do so through the Outliner panel.