code: public void removeAttributeValue(CmsAttributeValueView reference, boolean force) {
  
          CmsAttributeHandler parentHandler = null;
          CmsAttributeValueView parentView = null;
          boolean removeParent = false;
  
          CmsEntityAttribute attribute = m_entity.getAttribute(m_attributeName);
          if (isChoiceHandler() && attribute.isSingleValue()) {
              // removing last choice value, so remove choice itself
              parentHandler = (CmsAttributeHandler)m_parentHandler;
              parentView = reference.getParentView();
              removeParent = true;
          }
  
          if (attribute.isSingleValue() && !force) {
  
              reference.removeValue();
              if (!attribute.isSimpleValue()) {
                  removeHandlers(0);
              }
              m_entity.removeAttribute(m_attributeName);
          } else {
              int index = reference.getValueIndex();
              if (attribute.isComplexValue()) {
                  removeHandlers(index);
                  CmsEntity value = attribute.getComplexValues().get(index);
                  m_entity.removeAttributeValue(m_attributeName, index);
                  m_entityBackEnd.removeEntity(value.getId());
              } else {
                  m_entity.removeAttributeValue(m_attributeName, index);
              }
              reference.removeFromParent();
              m_attributeValueViews.remove(reference);
  
          }
          updateButtonVisisbility();
          if (removeParent && (parentHandler != null) && (parentView != null)) {
              parentHandler.removeAttributeValue(parentView);
              parentView.setCollapsed(false);
          }
          CmsUndoRedoHandler handler = CmsUndoRedoHandler.getInstance();
          if (handler.isIntitalized()) {
              handler.addChange(m_entity.getId(), m_attributeName, 0, ChangeType.remove);
          }
  
      }
docs: Removes the reference attribute value view.<p>
  
  @param reference the reference view
  @param force <code>true</code> if the widget should be removed even if it is the last one