“How do I make sure stuff I delete from my Mac trash is gone forever?”
When you Empty Trash the files are still there even though you can’t see it. Only when those files are overwritten with new files will they really be gone. So we need to write over those files to securely remove them and be sure no third party applications can access those deleted files.
So on the Mac most people just right click on the Trash can and select “Empty Trash”, but we want to premantely remove those Trash files.
Here’s how to delete your Trash files permanently and securely:
Press the Command key + right click and select “Securely Empty Trash”.
If you have no right click for whatever reason you can also use Control+Command+Left Click.