how to cancel subscription to window.cookieStore.addEventListener('change', ) in angular service

I am using angular: 15.2.10 for my project. I have created an angular service which can listen to cookie changes by leveraging the CookieStore Api. My current code looks as follows:

type CookieChangeType = {
    name: string,
    value: string,
    expires: Date,
    domain: string,
}

interface CookieChangeEvent extends Event {
    changed: CookieChangeType[]
}

type CookieStore = {
    addEventListener: Window["addEventListener"]
}

declare global {
    interface Window {
        cookieStore: CookieStore;
        addEventListener(type: String, listener: (this: Window, ev: CookieChangeEvent) => any, useCapture?: boolean): void;
    }
} 

export class CookieConsentCommonsService {
     
    
    subscribeToConsentCookieChange(callback: () => void): void {
            window.cookieStore.addEventListener('change', (event: CookieChangeEvent) => {
                console.log(`Cookie changed: ${change.name} = ${change.value}`);
                callback();            
            });
    }
}

This code works as expected. On the top of that I would like to be able to cancel the subscription. I have tried to store the subscription for later :

            const sub = window.cookieStore.addEventListener( ...);
            console.log("sub " + sub)

But there is no return from this code and the output message is:

sub undefined

How can I retrieve a reference for created subscription and later on use it to cancel the subscription?

https://developer.mozilla.org/zh-CN/docs/Web/API/EventTarget/removeEventListener

function handleChange() {
  // ...
}

// sub
window.cookieStore.addEventListener('change', handleChange);
// unsub
window.cookieStore.removeEventListener('change', handleChange);

or

const controller = new AbortController();

// sub
window.cookieStore.addEventListener('change', handleChange, { signal: controller.signal });
// unsub
controller.abort();

ts

// Cookie interface definition
interface Cookie {
  name: string;
  value: string;
  expires?: Date | null; // Optional expiration time
  path?: string; // Optional path
  domain?: string; // Optional domain
  secure?: boolean; // Optional secure flag
  sameSite?: 'lax' | 'strict' | 'none'; // Optional SameSite attribute
}

// CookieStore interface inheriting from EventTarget
interface CookieStore extends EventTarget {
  get(name: string): Promise<Cookie | null>;
  getAll(): Promise<Cookie[]>;
  set(cookie: Cookie): Promise<void>;
  delete(name: string): Promise<void>;
}

// Adding CookieStore to the global window object
declare global {
  interface Window {
    cookieStore: CookieStore;
  }
}