I thought that clicking the ‘X’ on a track merely closed the track view. Now it appears it “removes it from the project”. Is it possible to recover the audio?
If you haven’t closed the project, Edit > Undo will bring the track back. If you have close the project then the track is gone.
– Bill
Thanks, Bill. That’s a shame, though.
IMHO, it shouldn’t be an ‘X’, it should be a trash can icon. Just lost an hour’s work 
It’s not trash when you have the program open. It’s Delete with UNDO.
A side note that Audacity Projects don’t save UNDO. They save just about everything else but the ability to back up.
Once you close Audacity it flushes all its temporary memory and workspaces (like a proper program) and starts over.
Koz
With all due respect, in my pea brain: trash = delete w/ or w/o undo. I have been trained by Windows, OS X and Linux that X = close.