code: public static IMolecularFormula removeElement(IMolecularFormula formula, IElement element) {
          for (IIsotope isotope : getIsotopes(formula, element)) {
              formula.removeIsotope(isotope);
          }
          return formula;
      }
docs: Removes all isotopes from a given element in the MolecularFormula.
  
  @param  formula   IMolecularFormula molecularFormula
  @param  element   The IElement of the IIsotopes to be removed
  @return           The molecularFormula with the isotopes removed