code: def remove_tenant_user(request, project=None, user=None, domain=None):
      
      client = keystoneclient(request, admin=True)
      roles = client.roles.roles_for_user(user, project)
      for role in roles:
          remove_tenant_user_role(request, user=user, role=role.id,
                                  project=project, domain=domain)
docs: Removes all roles from a user on a tenant, removing them from it.