code: public void removeUserFromRole(CmsObject cms, CmsRole role, String username) throws CmsException {
  
          m_securityManager.removeUserFromGroup(cms.getRequestContext(), username, role.getGroupName(), true);
      }
docs: Removes a user from a role, in the given organizational unit.<p>
  
  @param cms the opencms context
  @param role the role to remove the user from
  @param username the name of the user that is to be removed from the group
  
  @throws CmsException if operation was not successful