bury one's head in the sand

/B EH1 R IY0 W AH0 N EH0 S EH0 D IH0 N DH AH0 S AE0 N D/
verb
  1. 1

    To deliberately ignore the reality of a situation; to pretend a problem does not exist.

Source: https://en.wiktionary.org/wiki/bury%20one's%20head%20in%20the%20sand