Procedure:
1. either drag an image onto AD´s icon in the dock or drag it aside the canvas; it will be locked and visible.
2. drag the image to trash
3. AD will prompt with this error:
4. you can´t work around it because macOS trash is blocked; you can´t simply try to put the image back.
5. Hit "OK" and your file will be gone for ever.
Conclusion: Drag an image explicit to the canvas if you prefer drag&drop or use "Place..." from the File menu. When it received a "Lock" as a property don´t delete image (move to the Trash) or you will loose that file.
Cheers