code: def del_functions(self, names):
          
          if isinstance(names, string_types):
              names = [names]
          for name in names:
              self._functionlib.pop(name)
docs: Removes the specified function names from the function library.
  
          Functions are removed from this instance of the array; all copies
          and slices of this array will also have the functions removed.
  
          Parameters
          ----------
          names : (list of) string(s)
              Name or list of names of the functions to remove.