[oblosys]

For me that didn't work. The red badge on System Preferences disappeared, but it came back the next day. Doing a `defaults delete com.apple.preferences.softwareupdate LatestMajorOSSeenByUserBundleIdentifier` got rid of it permanently.

[dmix]

Sorry I missed the second half, I fixed my comment:

> sudo softwareupdate --ignore "macOS Catalina"

It uses the label in the software update catalog to filter out specific updates.

You can get rid of it with:

> sudo softwareupdate --reset-ignored