Microsoft has already announced the release of Windows 10 for this summer 2015 and since then many Windows 7, 8 or 8.1 users have received an invitation to reserve
their copy the latest version of Windows.
You find this notification annoying? You don't intend on upgrading to Windows 10? No problem, you can disable this notification by uninstalling the KB3035583
Uninstalling updates is really easy, here's the step by step procedure: Windows 8.1 - How to uninstall updates
Do not forget to reboot your computer after uninstallation.