expunge vs flush out

expunge

verb
  • To erase or strike out. 

  • To eliminate completely; to annihilate. 

  • To delete permanently (e-mail etc.) that was previously marked for deletion but still stored. 

flush out

verb
  • To flesh out. 

  • To drive out or expose something or someone, as a game bird or other game animal from cover. 

  • Used other than figuratively or idiomatically: see flush, out. 

How often have the words expunge and flush out occurred in a corpus of books? (source: Google Ngram Viewer )