Deleting files gives Error Message

I have been getting an error message whenever I try to delete a file or folder. Can someone explain why I am getting this error? I am the Admin/root user of those files. And yes, as it says make sure “Locked” is deselected I checked it and it wasn’t selected in the first place.

Screenshot 2020-09-04 at 4.34.29 PM

and is it just I or 5 hours for 75 GB Transfer is normal from one shared folder to another?

Screenshot 2020-09-04 at 5.02.12 PM