func (s *ServicesService) DeleteDroneCIService(pid interface{}, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/drone-ci", pathEscape(project))
	req, err := s.client.NewRequest("DELETE", u, nil, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
DeleteDroneCIService deletes Drone CI service settings for a project.

GitLab API docs:
https://docs.gitlab.com/ce/api/services.html#delete-drone-ci-service
package gitlab
import (
	"encoding/json"
	"fmt"
	"strconv"
	"time"
)
type ServicesService struct {
	client *Client
}
type Service struct {
	ID                       int        `json:"id"`
	Title                    string     `json:"title"`
	CreatedAt                *time.Time `json:"created_at"`
	UpdatedAt                *time.Time `json:"updated_at"`
	Active                   bool       `json:"active"`
	PushEvents               bool       `json:"push_events"`
	IssuesEvents             bool       `json:"issues_events"`
	ConfidentialIssuesEvents bool       `json:"confidential_issues_events"`
	MergeRequestsEvents      bool       `json:"merge_requests_events"`
	TagPushEvents            bool       `json:"tag_push_events"`
	NoteEvents               bool       `json:"note_events"`
	ConfidentialNoteEvents   bool       `json:"confidential_note_events"`
	PipelineEvents           bool       `json:"pipeline_events"`
	JobEvents                bool       `json:"job_events"`
	WikiPageEvents           bool       `json:"wiki_page_events"`
}
type SetGitLabCIServiceOptions struct {
	Token      *string `url:"token,omitempty" json:"token,omitempty"`
	ProjectURL *string `url:"project_url,omitempty" json:"project_url,omitempty"`
}
func (s *ServicesService) SetGitLabCIService(pid interface{}, opt *SetGitLabCIServiceOptions, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/gitlab-ci", pathEscape(project))
	req, err := s.client.NewRequest("PUT", u, opt, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
func (s *ServicesService) DeleteGitLabCIService(pid interface{}, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/gitlab-ci", pathEscape(project))
	req, err := s.client.NewRequest("DELETE", u, nil, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
type SetHipChatServiceOptions struct {
	Token *string `url:"token,omitempty" json:"token,omitempty" `
	Room  *string `url:"room,omitempty" json:"room,omitempty"`
}
func (s *ServicesService) SetHipChatService(pid interface{}, opt *SetHipChatServiceOptions, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/hipchat", pathEscape(project))
	req, err := s.client.NewRequest("PUT", u, opt, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
func (s *ServicesService) DeleteHipChatService(pid interface{}, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/hipchat", pathEscape(project))
	req, err := s.client.NewRequest("DELETE", u, nil, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}
type DroneCIService struct {
	Service
	Properties *DroneCIServiceProperties `json:"properties"`
}
type DroneCIServiceProperties struct {
	Token                 string `json:"token"`
	DroneURL              string `json:"drone_url"`
	EnableSSLVerification bool   `json:"enable_ssl_verification"`
}
func (s *ServicesService) GetDroneCIService(pid interface{}, options ...OptionFunc) (*DroneCIService, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/services/drone-ci", pathEscape(project))
	req, err := s.client.NewRequest("GET", u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	svc := new(DroneCIService)
	resp, err := s.client.Do(req, svc)
	if err != nil {
		return nil, resp, err
	}
	return svc, resp, err
}
type SetDroneCIServiceOptions struct {
	Token                 *string `url:"token" json:"token" `
	DroneURL              *string `url:"drone_url" json:"drone_url"`
	EnableSSLVerification *bool   `url:"enable_ssl_verification,omitempty" json:"enable_ssl_verification,omitempty"`
}
func (s *ServicesService) SetDroneCIService(pid interface{}, opt *SetDroneCIServiceOptions, options ...OptionFunc) (*Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, err
	}
	u := fmt.Sprintf("projects/%s/services/drone-ci", pathEscape(project))
	req, err := s.client.NewRequest("PUT", u, opt, options)
	if err != nil {
		return nil, err
	}
	return s.client.Do(req, nil)
}