Using GWX Control Panel (formerly GWX Stopper) to Permanently Remove the 'Get Windows 10' Icon
GWX Control Panel (previously named GWX Stopper) is a free program that you can use to do the following on Windows 7 and Windows 8:
Remove the 'Get Windows 10' icon that appears in your notification area.
Prevent your Windows Update control panel from upgrading your computer to Windows 10.
Prevent your computer from secretly downloading Windows 10 installation files.
Detect and remove the hidden Windows 10 installation files if they're already on your PC.
'GWX Control Panel really works, is safe and easy to use, and gives you the option to re-enable the icon and upgrade notifications if you're ever ready to move forward with Windows 10.
UPDATE (November 1, 2015): Due to popular demand, version 1.5 of the program now includes the ability to delete the hidden Windows 10 installation folders (Windows.~BT and Windows.~WS). There are a few other features intended to improve the user experience and assist tech support staff who use GWX Control Panel to remotely help customers. There was a LOT of under-the-hood work done in this release- please let me know in the comments or on the Ultimate Outsider Facebook page if you see unexpected behavior."