The best way to securely delete files from your computer is to:

1. Empty your Recycle Bin or Trash. This will delete any files you sent to the bin or trash.
   
2. Back up important files securely. Make sure your back-up files are securely stored and encrypted.
   
3. Run a file eraser. You can use third-party file erasers, such as CCleaner, to securely delete files and overwrite empty space on your hard drive.
   
4. Perform a factory reset. If you would like to completely reset your system to its original state, you may want to do a factory reset.