I can’t empty the Trash

The operating system locks files that it’s using or previewing, so if you can’t empty the Trash entirely there’s a good chance one of its contents is still required by macOS or an app. Quit your apps and try again. If that doesn’t work, it could be that one of its contents is locked. Click Finder in the menu bar, hold Alt and click the Empty Trash option (note that the ellipsis after it disappears when Alt is held, meaning you won’t be asked to provide additional instruction in a dialog). Still no luck? Open Terminal, enter sudo rm ~/.Trash.* and provide an admin account’s name and password as confirmation, then press ® . Back up first!