go away vs slope off

go away

verb
  • To depart or leave a place. 

  • To travel somewhere, especially on holiday or vacation. 

  • To vanish or disappear. 

intj
  • A command encouraging someone to leave. 

slope off

verb
  • To depart quietly, without being noticed. 

How often have the words go away and slope off occurred in a corpus of books? (source: Google Ngram Viewer )