Never 10 gives you control over whether Windows 7 or 8.1 will upgrade itself to Windows 10. Video tutorial available.
In July of 2015, Microsoft added features to its Windows Update facility which allow it to be configured, on a machine-by-machine basis, to not forcibly upgrade qualifying Windows 7 and 8.1 operating systems to Windows 10. However, Microsoft did not make this configuration simple. It requires the use of the group policy editor (which is not present in some qualifying systems) and/or the system registry.
Since this utility simply updates and/or configures the system to prevent or allow OS upgrading, it may be deleted after it has configured the system appropriately.
Using this utility, inexperienced users will be able to easily use Never10 themselves, while advanced users will likely appreciate that fact that no additional software is installed and will be able to refer friends and family, whom they support, to this easy-to-use utility.