How Do I Securely And Permanently Remove A File In OS X?
This method is only recommended for those users who are familiar with the Terminal. First, find the path of the file you want to remove and then launch the Terminal app. Type srm /path/to/file, replacing "/path/to/file" with the path of the file you would like to remove. Hit enter and you're done. Note: this may take a few moments because it overwrites the file 35 times to ensure it cannot be recovered.