Can I undo 'softwareupdate'? Recently I was persuaded by a message from my Homebrew update process to (unthinkingly) run 

softwareupdate --all --install --force


forgetting that among the pending updates I had was the problematic 10.15.4 update. I literally (used correctly) cannot afford to have a bricked or compromised Mac, and so far I've had no problems, but I'd rather be sure.

Is there a way to undo softwareupdate (I haven't yet rebooted)?
To undo the effect of software updates, restore to a point in time before the update from backup. TimeMachine makes this rather simple, other backup methods (e.g. if you only run weekly backups) may require that you first offload any documents changed since the last backup.