There's no way that I can think of to tell BRU to determine when to delete the last word or the word following the track number.
You will need to filter which files you want to work on, but there's no way we can tell you how to filter the files with the information given.
I can show you how to delete the last word or the word following the track number, but as I say you will need to filter the files somehow.
To delete the word following the track number:
RegEx (1)
Match: (\d*-)[^\s]*\s(.*)
Replace: \1\2
This changes "
01-Devo Whip it.wav" to "
01-Whip it.wav"
To delete the last word before the file extension:
RegEx (1)
Match: (.*)\s\w*$
Replace: \1
This changes "
01-Whip it Devo .wav" to "
01-Whip it.wav"