On June 1st 2015, qualifying Windows 7 and Windows 8.1 PCs and tablets will start seeing the Get Windows 10 icon in their taskbar notification area to be able to reserve your free upgrade to Windows 10 today for when released on July 29th 2015.
When you reserve, you can confirm your device is compatible with Windows 10. Between reservation and when your upgrade is ready, the files you need for the upgrade will be downloaded to your PC to make the final installation go more quickly. Then, when your upgrade is ready after July 29, 2015, you get a notification that lets you get started with your upgrade.
You can cancel your reservation at any time prior to installing Windows 10.
This tutorial will show you how to cancel your reservation for a free upgrade to Windows 10 from Windows 7 or Windows 8.1 in the Get Windows 10 app.