I am preparing a chronology for an academic conference, so I need to place the repeal under the correct year. Any help would be most appreciated.
Recitals of the Rescript in education were abolished in 1946 with the enactment of the Fundamental Law of Education. Officially, resolutions to repeal the Rescript were passed by both houses on 19 June 1948. I used the Japanese Wikipedia as a quick source, which is reasonably accurate on such basic facts (though notorious for its lack of citations). More official source for the date is the House of Councillors webpage on the resolution.