code: public void unsubscribeResourceFor(CmsObject cms, CmsPrincipal principal, CmsResource resource)
      throws CmsException {
  
          if (!isEnabled()) {
              throw new CmsRuntimeException(Messages.get().container(Messages.ERR_SUBSCRIPTION_MANAGER_DISABLED_0));
          }
          m_securityManager.unsubscribeResourceFor(cms.getRequestContext(), getPoolName(), principal, resource);
      }
docs: Unsubscribes the principal from the resource.<p>
  
  @param cms the current users context
  @param principal the principal that unsubscribes from the resource
  @param resource the resource to unsubscribe from
  
  @throws CmsException if something goes wrong