Choices:
* Try in an Hour
* Try Tonight
* Remind Me Tomorrow

Where in Hell is the “Remind Me Next Year” choice? Everything is working perfectly right now. Leave me alone.

First, I've never seen a MacOS update jack up a computer the way some Win ones do, but if you want to block those you can.

Just click the Apple icon at top left, then About this Mac, then Software Updates and uncheck the box for Automatically keep my Mac up to date. I believe this will kill app updates as well, but if you're anti-any-updates-ever-on-my-lawn that may be want you want. There's also an Advanced option there where you may try unchecking all but the app updates if you still want those to run.

 
If you don't want to be reminded about a particular update again, ever:
 
Open a Terminal window and enter:
 
softwareupdate --ignore [name of update]
 
Don't use the brackets, but use quotes around the name if it has spaces in it. You can still download the update from Apple and install it manually.