code: func (s *OrganizationsService) RemoveMember(ctx context.Context, org, user string) (*Response, error) {
  	u := fmt.Sprintf("orgs/%v/members/%v", org, user)
  	req, err := s.client.NewRequest("DELETE", u, nil)
  	if err != nil {
  		return nil, err
  	}
  
  	return s.client.Do(ctx, req, nil)
  }
docs: // RemoveMember removes a user from all teams of an organization.
  //
  // GitHub API docs: https://developer.github.com/v3/orgs/members/#remove-a-member