Hey there!
Are these notifications for normal OS updates? Or for an OS upgrade, (E.g. from Catalina to Big Sur)? Apologize, I forget what OS this thread was on.
I wouldn’t recommend ignoring important updates, as many times they are for security and bug fixes, but understand why you’d want to, so if so this should work, just remember if and when you’re ready to do an update, you have to tell your Mac to do so, likewise, when using sudo to make changes, keep a backup of your data. (Although I’ve never had an issue with this, not everyone’s set up is the same):
If it’s just stopping OS software update prompts, I believe even in Bug Sur this would still work:
Open Terminal in Finder > Applications > Utilities.
Enter this command and press Return afterwards:
sudo softwareupdate --ignore
I believe if you wanted to ignore a full OS upgrade, (To Big Sur for example), you’d run, instead:
sudo softwareupdate --ignore "macOS Big Sur”
If and when prompted, enter your Admin password, (Note, you will not see anything show up when typing in Terminal, but you can press Return after entering the command).
And likewise, if and when you wanted to reset those changes, you can run:
sudo softwareupdate --reset-ignored
Hope that helps!