Can't Open Audacity, says it's already running

Help! Every time I try and open Audacity I get a pop-up saying it’s already running on my computer, but I have no idea where I can access it or close it. I’ve deleted and redownloaded the application several times, how is this still possible and how do I actually use the app again.
Screen Shot 2018-02-06 at 1.54.15 PM.png

Go to ~/Library/Application Support/audacity. Delete the “SessionData” folder.
– Bill