Files are deleted on pc but not on passport hard drive

I am new to the WD forum commmunity. I apologize if this has been previously asked.  I have an WD external drive connected to my Windows 7 PC.   I wanted to do a test to confirm the backup process was working okay, so I made some file changes and saw that those changes were automatically backed up to the passport external hard drive.  However I also noticed when I deleted a file on my pc, the same file was not deleted on my passport hard drive.  Can anyone help me on this? Thank you.

Hello gsmail, what you are describing is called a sync program, backup programs will not delete the files on the destination drive when deleted on the origin. Using Google you can find several programs that work the way you describe.