This tweak will change the default method used when you Empty Trash to Secure Empty Trash, which permanently erases and overwrites the deleted files.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To enable this setting, type (or copy and paste) the following command:
defaults write com.apple.finder EmptyTrashSecurely -boolean true
To reset this setting to the default value, type (or copy and paste) the following command:
defaults write com.apple.finder EmptyTrashSecurely -boolean false
To activate this tweak immediately, type the following command, or wait until the next reboot:
Close the Terminal session by typing
exit at the prompt.
Note: When the trash is emptied securely there is no way to recover the files once deleted, so ensure you do not accidentally put any files you want to keep in the Trash.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.