Between Riccardo Mori's piece on Catalina and Michael Tsai's excellent writings, I flat out don't want to update to Catalina. But I'm also tired of Apple prompting (harassing) me to update. Here's how to stop it

  1. Apple menu.
  2. System Preferences
  3. Software Update
  4. Advanced
  5. Turn off Check for Updates

This is the first time I've ever turned these options off. Normally I just say no to it until it is time to do an update; this time I don't have any clue when that might be.

Note: Apple has changed this from 2017. If you aren't running Mojave then this may help you.