How to Securely Empty Trash in MacOS
The default empty trash function in macOS isn't very secure. Data isn't actually overwritten; rather, macOS merely tells itself that the portion of the hard drive containing the deleted data can now be used to store new data, eventually overwriting it.
When you "securely empty" the trash, your computer will write a series of 0s over the old data, effectively destroying it. You used to be able to do this by simply changing your preferences. Like the beloved MacOS Dashboard, Apple has removed that feature in 2019.
Now, you must perform two steps when emptying your trash on your Mac.