In the RoleService
override def removeRoleFromUserById (uid: UserId, rid: RoleId): M[ValidatedNel[Error, Int]]= {
    roleRepo.removeRoleFromUserById(uid,rid).map{
      case 0 => invalidNel(NotFound(s"Nothing has been deleted"))
      case x => valid(x)
    }
  }

In the RoleController
def removeRoleFromUser(userId: Long, roleId: Long) = authorized(ROLE_DELETE).async { implicit req =>
    roleService.removeRoleFromUserById(UserId(userId), RoleId(roleId)) map {
      case Invalid(nel) => BadRequest(nel.toList.mkString(","))
      case Valid(r) => Ok(s"$r rows has been deleted")
    } recover {
      case NonFatal(ex) => InternalServerError(ex.toString)
    }
  }