MacOS - /Library/Updates - Is it safe to delete or not?
I would say no. I have people move other files to an external drive if they are not sure their backup is solid. If you have a solid backup, you can just delete files.
Once you have 10 GB free run the updates until you are clear of this.
sudo softwareupdate -aiR

Quit all apps before or right after you start this (except terminal app of course).