func (s *UsersService) Unfollow(user string) (*Response, error) {
	u := fmt.Sprintf("user/following/%v", user)
	req, err := s.client.NewRequest("DELETE", u, nil)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
Unfollow will cause the authenticated user to unfollow the specified user.

GitHub API docs: http://developer.github.com/v3/users/followers/#unfollow-a-user
package github
import "fmt"
func (s *UsersService) ListFollowers(user string, opt *ListOptions) ([]User, *Response, error) {
	var u string
	if user != "" {
		u = fmt.Sprintf("users/%v/followers", user)
	} else {
		u = "user/followers"
	}
	u, err := addOptions(u, opt)
	if err != nil {
		return nil, nil, err
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	users := new([]User)
	resp, err := s.client.Do(req, users)
	if err != nil {
		return nil, resp, err
	}
	return *users, resp, err
}
func (s *UsersService) ListFollowing(user string, opt *ListOptions) ([]User, *Response, error) {
	var u string
	if user != "" {
		u = fmt.Sprintf("users/%v/following", user)
	} else {
		u = "user/following"
	}
	u, err := addOptions(u, opt)
	if err != nil {
		return nil, nil, err
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	users := new([]User)
	resp, err := s.client.Do(req, users)
	if err != nil {
		return nil, resp, err
	}
	return *users, resp, err
}
func (s *UsersService) IsFollowing(user, target string) (bool, *Response, error) {
	var u string
	if user != "" {
		u = fmt.Sprintf("users/%v/following/%v", user, target)
	} else {
		u = fmt.Sprintf("user/following/%v", target)
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return false, nil, err
	}
	resp, err := s.client.Do(req, nil)
	following, err := parseBoolResponse(err)
	return following, resp, err
}
func (s *UsersService) Follow(user string) (*Response, error) {
	u := fmt.Sprintf("user/following/%v", user)
	req, err := s.client.NewRequest("PUT", u, nil)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}