code: public void removeFieldValues(String fieldName, Collection<String> values) {
          Utils.require(!Utils.isEmpty(fieldName), "fieldName");
          if (values != null && values.size() > 0) {
              List<String> valueSet = m_valueRemoveMap.get(fieldName);
              if (valueSet == null) {
                  valueSet = new ArrayList<String>();
                  m_valueRemoveMap.put(fieldName, valueSet);
              }
              valueSet.addAll(values);
          }
      }
docs: Add "remove" values for the given field. This method should only be called for MV
  scalar and link fields. When the updates in this DBObject are applied to the
  database, the given set of values are removed for the object. An exception is
  thrown if the field is not MV. If the given set of values is null or empty, this
  method is a no-op.
  
  @param fieldName Name of an MV field to remove" values for.
  @param values    Collection values to remove for the field.