code: func getSignableRolesForTargetAndRemove(releasedTarget client.Target, notaryRepo client.Repository) error {
  	signableRoles, err := trust.GetSignableRoles(notaryRepo, &releasedTarget)
  	if err != nil {
  		return err
  	}
  	// remove from all roles
  	return notaryRepo.RemoveTarget(releasedTarget.Name, signableRoles...)
  }
docs: // get all the roles that signed the target and removes it from all roles.