uninform

From un- +‎ inform, or a back-formation from uninformed.

uninform (third-person singular simple present uninforms, present participle uninforming, simple past and past participle uninformed)

1. (transitive) To revert (someone) to an uninformed state; reverse the informing of
   • 2011, Bernard Knight, According to the Evidence:

     After the coroner is informed, it's virtually impossible to uninform him!

   • 2013, Harriet Taylor, Pieter Hogenbirk, Information and Communication Technologies in Education:

     Another characteristic of the subject is the educability, that is, to uninform and to exclude.

   • 2015, Margaret Feinberg, Fight Back With Joy:

     She jotted a note on her clipboard. “I'm pretty sure it's nothing.” “Most lumps are just thick tissue,” she explained. “But we have to be sure. Because you informed me, we're required to schedule an ultrasound.” “Is there a way to uninform you?” I asked.