You could do it without VBA
Press CTRL + A
Click Edit - Goto - Special - Constants - uncheck all except Errors - OK
Right Click - Clear Contents
Change Constants to Formulas if these are actually formulas.
But since you said data was imported, it sounds like they are constants that WERE formulas in the file the data was imported from.
If it must be a macro, use the macro recorder (tools - macro - record new macro) to record the above steps.
Hope that helps.