func (s *AccessRequestsService) DenyGroupAccessRequest(gid interface{}, user int, options ...RequestOptionFunc) (*Response, error) {
	group, err := parseID(gid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("groups/%s/access_requests/%d", pathEscape(group), user)
	req, err := s.client.NewRequest(http.MethodDelete, u, nil, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
DenyGroupAccessRequest denies an access request for the given user.

GitLab API docs:
https://docs.gitlab.com/ce/api/access_requests.html#deny-an-access-request
package gitlab
import (
	"fmt"
	"net/http"
	"time"
)
type AccessRequest struct {
	ID          int              `json:"id"`
	Username    string           `json:"username"`
	Name        string           `json:"name"`
	State       string           `json:"state"`
	CreatedAt   *time.Time       `json:"created_at"`
	RequestedAt *time.Time       `json:"requested_at"`
	AccessLevel AccessLevelValue `json:"access_level"`
}
type AccessRequestsService struct {
	client *Client
}
type ListAccessRequestsOptions ListOptions
func (s *AccessRequestsService) ListProjectAccessRequests(pid interface{}, opt *ListAccessRequestsOptions, options ...RequestOptionFunc) ([]*AccessRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/access_requests", pathEscape(project))
	req, err := s.client.NewRequest(http.MethodGet, u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	var ars []*AccessRequest
	resp, err := s.client.Do(req, &ars)
	if err != nil {
		return nil, resp, err
	}
	return ars, resp, err
}
func (s *AccessRequestsService) ListGroupAccessRequests(gid interface{}, opt *ListAccessRequestsOptions, options ...RequestOptionFunc) ([]*AccessRequest, *Response, error) {
	group, err := parseID(gid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("groups/%s/access_requests", pathEscape(group))
	req, err := s.client.NewRequest(http.MethodGet, u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	var ars []*AccessRequest
	resp, err := s.client.Do(req, &ars)
	if err != nil {
		return nil, resp, err
	}
	return ars, resp, err
}
func (s *AccessRequestsService) RequestProjectAccess(pid interface{}, options ...RequestOptionFunc) (*AccessRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/access_requests", pathEscape(project))
	req, err := s.client.NewRequest(http.MethodPost, u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	ar := new(AccessRequest)
	resp, err := s.client.Do(req, ar)
	if err != nil {
		return nil, resp, err
	}
	return ar, resp, err
}
func (s *AccessRequestsService) RequestGroupAccess(gid interface{}, options ...RequestOptionFunc) (*AccessRequest, *Response, error) {
	group, err := parseID(gid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("groups/%s/access_requests", pathEscape(group))
	req, err := s.client.NewRequest(http.MethodPost, u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	ar := new(AccessRequest)
	resp, err := s.client.Do(req, ar)
	if err != nil {
		return nil, resp, err
	}
	return ar, resp, err
}
type ApproveAccessRequestOptions struct {
	AccessLevel *AccessLevelValue `url:"access_level,omitempty" json:"access_level,omitempty"`
}
func (s *AccessRequestsService) ApproveProjectAccessRequest(pid interface{}, user int, opt *ApproveAccessRequestOptions, options ...RequestOptionFunc) (*AccessRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/access_requests/%d/approve", pathEscape(project), user)
	req, err := s.client.NewRequest(http.MethodPut, u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	ar := new(AccessRequest)
	resp, err := s.client.Do(req, ar)
	if err != nil {
		return nil, resp, err
	}
	return ar, resp, err
}
func (s *AccessRequestsService) ApproveGroupAccessRequest(gid interface{}, user int, opt *ApproveAccessRequestOptions, options ...RequestOptionFunc) (*AccessRequest, *Response, error) {
	group, err := parseID(gid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("groups/%s/access_requests/%d/approve", pathEscape(group), user)
	req, err := s.client.NewRequest(http.MethodPut, u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	ar := new(AccessRequest)
	resp, err := s.client.Do(req, ar)
	if err != nil {
		return nil, resp, err
	}
	return ar, resp, err
}
func (s *AccessRequestsService) DenyProjectAccessRequest(pid interface{}, user int, options ...RequestOptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/access_requests/%d", pathEscape(project), user)
	req, err := s.client.NewRequest(http.MethodDelete, u, nil, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}