revoke vs walk back

revoke

verb
  • To cancel or invalidate by withdrawing or reversing. 

noun
  • The act of revoking in a game of cards. 

  • A violation ranked in seriousness somewhat below overt cheating, with the status of a more minor offense only because, when it happens, it is usually accidental. 

  • A renege; a violation of important rules regarding the play of tricks in trick-taking card games serious enough to render the round invalid. 

walk back

verb
  • To withdraw or backpedal on a statement or promise. 

  • Used other than figuratively or idiomatically: see walk, back. 

How often have the words revoke and walk back occurred in a corpus of books? (source: Google Ngram Viewer )