pretend the whole thing never existed 
(ROOT (S (VP (VB pretend) (SBAR (S (NP (DT the) (JJ whole) (NN thing)) (ADVP (RB never)) (VP (VBD existed)))))))
(ROOT (S (VP (VB ) (SBAR (S (NP (DT ) (JJ ) (NN )) (ADVP (RB )) (VP (VBD )))))))