Easiest way to be certain of never having issues with unwanted 'updates' to 10.....
For those who can't manage any other way....
Turn off Windows updates entirely. The world doesn't end if you do.
Most people will never know the difference...or miss them....or care....
That works only to a point.... as do the 3rd party programs and any other method to prevent 10.
As many have awoken to discover, even with Never 10 and GWX Control Panel installed, is that Win 10 was downloaded and installed during Scheduled Maintenance... and the only way to prevent that is to disconnect from the internet entirely. As Doc said, MS holds the keys to your OS, and such is its determination to see Win 10 on a billion devices by 2020, it is using any and all methods to deliver it to machines connected to the internet.
And yes, I am sure Win 10 is being downloaded and installed without consent and agreement to the terms. It happened on my second big beastie.... and yes, with Never 10 AND GWXCP installed. I shut down Win 8.1, went to bed and awoke to Win 10
As for the 'roll back', some people are finding that option greyed out, as was the case with my HP 2-in-1.... and others who do... can perform the roll back, do so in vain, with their machines being changed back to 10 a few days later. Again, I am sure of this, too.... being it happened on my 2nd big beastie.
In a nutshell, if MS wants you to have Win 10.... you'll GET it, like it or not.
Turning off Windows Update may also be in vain, as some reports suggest MS can remotely turn it back on again. As I recall, Wizaerd1956 said that his Windows Update settings had been changed, either remotely or by a rogue KB file that managed to sneak through.