There are a variety of reasons why you might want to determine the timing of a possible Windows 10 upgrade and one wrong click could render your PC unavailable for hours. If you would like to continue getting updates, without upgrading at this time, it's possible to turn off the upgrade prompt.
Depending upon your current operating system, you may begin to encounter this screen, when attempting to run your Windows updates.
How to turn off the upgrade prompt?
Just click on the "Show all available updates" hyperlink as shown here.
Once there, click on Optional updates and deselect the Win10 upgrade option.
Now, you can go about getting the regular updates you are looking for and you should not get prompted for the Win10 upgrade again.