Ubuntu – I cannot delete files from root’s Trash

You are trying to set permissions for a file system that isnt recognized. THE SYSTEM FUNCTION that "deletes" is not the system used in a linux based bit unless its emulated. When you tell it to delete it tries to write to the "trashbin". You are only moving stuff. To remove it you need to access the file system, not raw data. Its going to kick the data back because you are just asking it to move not delete, the delete command isnt within its wheelhouse./ regardless of the command you use.

If you can mount the partition/drive of the server in samba or what ever you like you may be able to use that to delete. Try virtually mounting, with permissions. If you only have read/write but not delete/move your going to have a bad time.

When nautilus trashes something, it doesn't want to have to move it across partitions. This is because it takes a lot longer to move between partitions, and then if you remove the partition then the trash has no place to restore to.

Anywhere that is on the same partitions as your home directory is sent to ~/.local/share/Trash. This works across the entire root partition on setups which only have one partition.

On any other partition nautilus will make a .Trash-1000 folder on the root of the partition, then send all trashed files into that. This works rather well on external drives that you have full read/write access to, though it won't work if you don't have write permission to the root of the drive.

Because your / partition isn't the same as your /home partition, and a .Trash-1000 doesn't exist with write permission at the root of your system, nautilus will fail to trash files. Thus the delete key won't work and a trash action won't be available in the menus.

You could try using a root nautilus and deleting one file so that the /.Trash-1000 folder is created correctly, then using sudo chmod -R 777 /.Trash-1000 to give yourself permission to access a trash on the / filesystem. I cannot confirm that this will work though you could give it a try.