code: function unregister(win, accelerator) {
  	let wc;
  	if (typeof accelerator === 'undefined') {
  		wc = ANY_WINDOW;
  		accelerator = win;
  	} else {
  		if (win.isDestroyed()) {
  			debug(`Early return because window is destroyed.`);
  			return;
  		}
  		wc = win.webContents;
  	}
  	if (Array.isArray(accelerator) === true) {
  		accelerator.forEach(accelerator => {
  			if (typeof accelerator === 'string') {
  				unregister(win, accelerator);
  			}
  		});
  		return;
  	}
  
  	debug(`Unregistering callback for ${accelerator} on window ${title(win)}`);
  
  	_checkAccelerator(accelerator);
  
  	debug(`${accelerator} seems a valid shortcut sequence.`);
  
  	if (!windowsWithShortcuts.has(wc)) {
  		debug(`Early return because window has never had shortcuts registered.`);
  		return;
  	}
  
  	const shortcutsOfWindow = windowsWithShortcuts.get(wc);
  
  	const eventStamp = toKeyEvent(accelerator);
  	const shortcutIdx = _findShortcut(eventStamp, shortcutsOfWindow);
  	if (shortcutIdx === -1) {
  		return;
  	}
  
  	shortcutsOfWindow.splice(shortcutIdx, 1);
  
  	// If the window has no more shortcuts,
  	// we remove it early from the WeakMap
  	// and unregistering the event listener
  	if (shortcutsOfWindow.length === 0) {
  		// Remove listener from window
  		shortcutsOfWindow.removeListener();
  
  		// Remove window from shortcuts catalog
  		windowsWithShortcuts.delete(wc);
  	}
  }
docs: Unregisters the shortcut of `accelerator` registered on the BrowserWindow instance.
  @param  {BrowserWindow} win - BrowserWindow instance to unregister.
  This argument could be omitted, in this case the function unregister the shortcut
  on all app windows. If you registered the shortcut on a particular window instance, it will do nothing.
  @param  {String|Array<String>} accelerator - the shortcut to unregister
  @return {Undefined}