Hello Jurian,
It's not possible to delete objects using a nanoflow, because nanoflows don't allow you to access the database (where the object has to be deleted aswell). In case you just want to stop showing the objects, you can simply remove them from the list. If you actually want to delete the list, you either have to use a microflow to delete the list, or use a non-perisistable helper object in your nanoflow which is connected to your entities what allows you to keep track of the list you want to delete, so you can delete it later using a microflow.
Kind regards,
Cas
A workaround that uses javascript actions can be found in the app store