Webster's Revised Unabridged Dictionary · 1913

Unteach

Unteach , transitive verb

[1st pref. un- + teach.]

1.
To cause to forget, or to lose from memory, or to disbelieve what has been taught.
Experience will unteach us. — Sir T. Browne
One breast laid open were a school Which would unteach mankind the lust to shine or rule. — Byron
2.
To cause to be forgotten; as, to unteach what has been learned. — Dryden