code: func (s *RepositoriesService) RemovePullRequestReviewEnforcement(ctx context.Context, owner, repo, branch string) (*Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/branches/%v/protection/required_pull_request_reviews", owner, repo, branch)
  	req, err := s.client.NewRequest("DELETE", u, nil)
  	if err != nil {
  		return nil, err
  	}
  
  	// TODO: remove custom Accept header when this API fully launches
  	req.Header.Set("Accept", mediaTypeRequiredApprovingReviewsPreview)
  
  	return s.client.Do(ctx, req, nil)
  }
docs: // RemovePullRequestReviewEnforcement removes pull request enforcement of a protected branch.
  //
  // GitHub API docs: https://developer.github.com/v3/repos/branches/#remove-pull-request-review-enforcement-of-protected-branch