This is a simple tip on how to hide the libvirt-qemu user from your login screen.
If you installed the KVM package using
apt on your Linux Mint 19.1 you may notice that a new user shows up on your login screen (at least if you’re using Cinnamon DE with LightDM).
You can hide it by running the following commands:
$ printf "[User]\nSystemAccount=true\n" | sudo tee /var/lib/AccountsService/users/libvirt-qemu $ sudo systemctl restart accounts-daemon.service
After logging out that user should be gone from your login screen.