unsay

verb2

1. •
   To withdraw, retract (something said).

   • And in the first place, you will be so good as to unsay that story about selling his head, which if true I take to be good evidence that this harpooneer is stark mad […] — 1851
2. •
   To cause something not to have been said; to make it so that one never said something (since this is physically impossible, usually in the subjunctive).

   • I wish I could unsay that.
   • There are some things I'd like to unsay... to my boss... right before he decided to fire me.