unprepare1
/ˌʌnprɪˈpɛː/verb
[with object] To undo the preparation of; to abandon or end a state of readiness or anticipation.
Origin
Late 16th century. From un- + prepare.
unprepare2
/ˌʌnprɪˈpɛː/verb
[with object] To make unprepared for something; to render unready or apprehensive. Formerly also with †to.
Origin
Mid 17th century; earliest use found in John Milton (1608–1674), poet and polemicist. From un- + prepare, after unprepared.