Files on an external hard drive that were moved to the Recycle Bin by another device cannot be seen or deleted by the device to which the drive is currently connected.

 External hard drives use their own hidden trash folders. If the file was moved to the trash by another device—such as a Mac, another Windows PC, or a router—specific restrictions apply depending on your operating system.

The reasons why you cannot see or delete them

Hidden folders

The file is located in a hidden folder on the external drive (for example, .$Trash on a Mac or a #recycle folder on a NAS).

Permission structure

The other device has locked the files. You are not the 'owner' of those specific files on your current device, causing your local computer to deny access.

OS-specific

Each operating system has its own hidden trash folder. Windows or macOS often ignores the specific trash folder of the other system.

How do you solve this?

Show hidden files

Make sure that hidden files and folders are visible in your File Explorer (Windows) or Finder (Mac). In Windows, you can find this under View > Show > Hidden items. In macOS, use the shortcut Command + Shift + Period.

Connect the drive to the original source

If the files were deleted from another device, they are sometimes only shown and deleted when the drive is reconnected to that specific device.

Disk check (Chkdsk)

The file structure might be corrupted. Open the Command Prompt in Windows, type chkdsk X: /f (replace X with the drive letter of your external drive), and press Enter.

Permanently delete

You can bypass the recycle bin and permanently erase the files from the drive. In Windows, you do this by selecting the files and using the key combination Shift + Delete.

Delete files without connecting the external hard drive to the previous device from which the files were deleted.

You can permanently delete these files from the external hard drive by manually locating and emptying the hidden system folder.
Below you will find the steps for both Windows and macOS.

Solution for Windows

If the external drive is now connected to a Windows PC, the previous device likely mapped the files to a hidden trash folder.

• Make hidden files visible: Open File Explorer and go to the external hard drive.
• Click View at the top (or the three dots ... in Windows 11) and choose Options.
• Go to the View tab.
• Check: Show hidden files, folders, and drives.
• Uncheck: Hide protected operating system files (Recommended). Click 'Yes' on the warning and then click Apply.
• Delete the trash folder: You will now see folders appear that were previously invisible.
• Look for folders such as $RECYCLE.BIN, .Trashes, or .Trash-1000.
• Select this folder and press Shift + Delete to permanently erase the contents immediately (bypassing the Windows Recycle Bin).

Solution for macOS (Mac)

If the external drive is now connected to a Mac, you can empty the hidden folders via Finder or the Terminal.

Method 1: Via Finder

• Open the external drive in Finder.
• Press the key combination Command + Shift + Period (.) to show hidden folders.
• Look for the folder .Trashes or $RECYCLE.BIN.
• Drag the contents to your Mac Trash and choose Empty Trash.

Method 2: Forced via Terminal (If Finder refuses)

• Open Terminal (via Spotlight or Applications > Utilities).
• Type exactly the following command, including the space at the end, but do not press Enter yet: sudo rm -rf
• Drag the folder .Trashes or $RECYCLE.BIN from your external drive directly into the Terminal window. The path to the folder will be filled in automatically.
• Press Enter.
• Type your Mac password (no characters will appear while typing) and press Enter. The files are now gone immediately.
• If you get a message about "no permissions" or "access denied" during deletion, please let me know.
• If you want, I can show you how to: Adjust permissions and ownership rights in Windows
• Adjust permissions and ownership rights in macOS
• Completely format the external drive (if it no contains no important data)

(source: Google Gemini)