I would recommend removing the preferences for VLC Media Player to see if that resolves the issue.
To do this, open a new Finder window, and then choose the Home option from the Go menu. Open the Library folder, and then open the Preferences folder.
Inside of this folder you will see several files. You will want to trash the following files/folders:
VLC (folder)
org.videolan.vlc.plist (file)
Once you've moved these files to the Trash, open VLC Media Player and then attempt to quit the application normally.