How to delete Gnome Boxes machine from bash

Yesterday I duplicated my Windows 10 machine in Gnome boxes to upgrade to Win 11. After realising that it would need 64 GB of space on my harddrive, which I do not have currently, I deleted the image. Now Gnome boxes crashes with the following error: (gnome-boxes:59538): Boxes-CRITICAL **: 09:44:24.321: boxes_vm_importer_get_source_media: assertion 'self != NULL' failed To me this sounds like a missing image (source_media). I would like to simply delete the machine that is referring to that image, but googling didn’t provide me with anything useful. Thanks for help