After searching through several versions of the play, I found that the Quartos (the first published in 1600 and the second in 1619) have Theseus say "moon used" in place of the Arden's "mure rased." This however, as most editors note, makes no sense in the context of the scene. After all, it is not Moonshine that has just exited, but Wall. Interestingly, the Folio (published in 1623) uses "morall downe." Harold Brooks, in his Arden appendix, posits that perhaps "rased" was replaced after an actor refused to say the line for fear that "rased" (raze=demolish) would be mistaken by the audience for its antonym "raised." R. A. Foakes, the editor of the Cambridge edition, writes that it is possible that the "morall" in the Folio came from the result of someone trying to correct "moon" with "wall" and having the resulting smudge be confused with "morall." In any case, the Arden uses "mure rased", the Pelican uses "mural down" and the Cambridge, Folger, and Oxford use "wall down."
Take your pick!