While testing a printer attached to a router, I ended up with hung print jobs I could not delete in the GUI of Budgie (hitting the trash would not delete the job). So I added the user root to the lpadmin group (usermod -a -G lpadmin root) and after that I was able to delete those jobs. The bug is perhaps present with Gnome version of Solus.
Ubuntu has a bug opened for something similar. They've fixed it in package cups-pk-helper.