By default, the items are moved to the Trash on your Mac Dock rather than being deleted immediately. It is abnormal that your Trash asks you to delete the items immediately, indicating that your Trash has some errors.
You can restart your Mac to see if the temporary system problems lead to the Trash that can't open on your Mac but delete files immediately.
If the issue still can't be fixed, you can re-create the Dock .plist file. That is to exclude if the Dock errors cause the abnormality of the Trash.
- Open Finder and click Go > Go to Folder on the top Finder menu bar.
- Enter ~/Library/Preferences/com.apple.dock.plist into the search box and hit Enter.
- Select the Dock .plist file and press Command + Shift + Delete to permanently delete it from your Mac.
- Restart your Mac to let the Dock .plist file automatically re-create.
You can also run Terminal to open the Trash on your Mac:
- Open Terminal.
- Enter open ~/.Trash.
Then, drag the file you want to delete to the Trash.
