Reference
Trash
Deleting in Atlas can be undone. Whatever you remove goes to the Atlas trash, separate from the Windows Recycle Bin, and waits there until you restore it or empty it.
Send to trash
Select one or more images and press Delete, or right-click and choose Delete. Atlas moves them to its trash and remembers where each one came from.
Get it back
Open Trash from the sidebar, right-click an item, and restore it to exactly where it was, or remove it for good.
Empty it
Clear All in the trash view deletes everything in it for good. That is the one delete in Atlas you cannot take back.