Definitions for unteachʌnˈtitʃ
Random House Webster's College Dictionary
to cause to be forgotten or disbelieved, as by contrary teaching.
to cause to forget or disbelieve something previously taught.
Origin of unteach:
cause to disbelieve; teach someone the contrary of what he or she had learned earlier
cause to unlearn
"teach somebody to unlearn old habits or methods"
To cause someone to unlearn; to make someone forget something they have been taught.
To cause something previously learned to be forgotten.
to cause to forget, or to lose from memory, or to disbelieve what has been taught
to cause to be forgotten; as, to unteach what has been learned