# Unset Variable Using condition or If

<< Notation
NotationClearNotations[];
NotationSymbolize[NotationTemplateTag[
\!$$\*OverscriptBox[\(\[Tau]$$, $$^$$]\)],
(*Overscript[\[Tau], ^] =1*)
ValueQ[
\!$$\*OverscriptBox[\(\[Tau]$$, $$^$$]\)]

\!$$\*OverscriptBox[\(\[Tau]$$, $$^$$]\) =. /; ValueQ[
\!$$\*OverscriptBox[\(\[Tau]$$, $$^$$]\)];

\!$$\*OverscriptBox[\(\[Tau]$$, $$^$$]\)


If ValueQ[] return False, why it still complains Unset "Assignment on OverHat for Overscript[\[Tau], ^] not found"

I just want to clear specific values of the OverHat or Subscript

When it runs again, it complains Symbolize Warning: The box structure attempting to be symbolized , even though I have added Notation'ClearNotations[];

Using If

OverHat[\[Rho]] Unset fails in If expression, but succeeds in OverHat[\[Rho]]=.

• Would If[ValueQ[t], t = .] work? Is it mandatory for you to use Condition? Jun 24 at 11:24
• No, I just want to clear the values of OverHat[v]. If works. Why Condition does not work? Jun 24 at 11:30
• Condition` is a pattern test function, and you have no pattern in your expression. Jun 24 at 11:33