Bottom Line: It is 100% safe to delete files inside /Library/Updates. macOS stores downloaded installer packages for macOS updates in this folder.
What is the /Library/Updates Folder?
Located at /Library/Updates/, when System Settings downloads a macOS update (e.g. macOS Sonoma or Sequoia installer), it saves the 12 GB installer .pkg to this directory.
How to Delete macOS Update Installers
sudo rm -rf /Library/Updates/*
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