Unable to delete empty folder in the trash on Mac Pro

Library folders are generally intended to be marked invisible to avoid accidental deletion.

command-shift-period toggles visibility.

There are in fact three Library folders, each of which are meant to remain locked

/Volumes/boot volume/Library

holds all the preferences, caches, and logs for operating system level applications

/Volumes/boot volume/System/Library

holds the same just for the installed operating system.

/Volumes/Users/yourname/Library

holds for that user account the same. Local email storage, and local user account settings for specific Apps are managed here.

If you move any of these three folders into your Trash bin, the system will balk at you. So put them back where you found them. Only delete those items in those folders you know don't belong.

Applications reported by Etrecheck that you know to be non-essential, should be reinstalled, and deleted with Freemacsoft AppCleaner. That will find those files in the Library folders associated with those Apps if those Apps don't have their own Uninstaller.

Outside of that, never trash a Library folder without knowing its source.

The fastest and most practical fix is to use Terminal. Just open Terminal from your Applications > Utilities folder, and type this command exactly: sudo rm -rf ~/.Trash/* — then hit Enter. It’ll ask for your admin password (don’t worry if nothing shows while you type), and once you enter it, that command will force-delete everything inside your Trash. If the file still refuses to go, you can run a couple of quick commands first to reset the file’s permissions: sudo chflags -R nouchg ~/.Trash followed by sudo chmod -R 755 ~/.Trash. These clear any “locked” status and fix access rights so the system can remove it. After that, go back and run the delete command again.

Restart your Mac just to make sure everything’s clean, and that annoying file should finally be gone for good.