You are using the Delete Folder button while you have checked items inside it.
For security reasons, we ask you to uncheck all items, and then use this button if you want to delete the entire Library folder.
If you instead want to delete the checked items, then use the Delete button next to Cut/Copy.
The entire Library folder and all its contents will be deleted.
If you want to delete specific checked items, use the Delete button next to Cut, Copy.
Are you sure you want to delete Library and all its contents?
The checked items will be permanently deleted and may not be recovered. Are you sure?