Removing the "installer media" iso file automatically deletes the VM created from it
Boxes 3.28.5 installed from flathub. Relevant console message:
(gnome-boxes:3): Boxes-WARNING **: 02:21:14.950: vm-creator.vala:100: Source installer media '/home/aleb/Downloads/ubuntu-17.10.1-desktop-amd64.iso' no longer exists. Deleting machine 'Ubuntu 17.10'..
A VM can hold important data, it should never be deleted automatically.
Edited by Alexandru Băluț