This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.1)

RemoveNotation

RemoveNotation[boxes DoubleLongLeftRightArrow expr]
removes the notation boxes DoubleLongLeftRightArrow expr.
RemoveNotation[boxesDoubleLongRightArrowexpr]
removes only the parsing.
RemoveNotation[boxesDoubleLongLeftArrowexpr]
removes only the formatting.