How can I cancel High Sierra installation?

[ergalthema]

I've been on Yosemite because I use software that isn't compatible with newer versions of OSX. I was prompted to install updates. I clicked to see what it wanted to install. It had one item that said "iTunes". I think it also said High Sierra, but it wasn't obvious that it would install an upgrade to the OS. It looked like an iTunes update (which happens regularly).

I clicked install, and the next thing I know it shows this: https://i.imgur.com/qUGYa0c.png
That shows two updates, when I only clicked on one. Seems like I was tricked...

And there is this window to install High Sierra: https://i.imgur.com/HwPN2gl.png

I see an option to "quit install macOS" - will that prevent the installation?
[doublepost=1531256503][/doublepost]I searched "quit install macOS" and found more info. I clicked it and deleted the installation file... whew!

 

[Fishrrman]

Type command-Q (quit).
Or go to the file menu and see if it offers a quit option.

If that doesn't work, pull the plug out of the wall.

 

[inscrewtable]

You can simply quit, this is what one does if one wants to make a boot disk.

1. When the macOS installer opens, quit it without continuing installation.

https://support.apple.com/en-au/ht201372