If you do not select the Move to the Recycle Bin option (or, if the file is located on a drive that does not have the Recycle Bin), then the deletion occurs differently: instead of moving the file to the Recycle Bin, Windows marks the blocks of the hard drive space occupied by the file as available for use by other files. The same happens when you delete the file with AB Commander and select the Move to the Recycle Bin option on the Delete window. If you use Windows Explorer to delete a file on a drive that has a Recycle Bin on it, then the file is not deleted at all! Instead, Windows moves it to the Recycle Bin, giving you (or someone else who gets hold of your disk) the possibility to restore the file you've 'deleted'.

To understand the need for this option, let's consider what happens under the hood when you delete a file. You've been probably wondering, why would you need that option? Isn't the Delete command supposed to do that by itself? If you've been using AB Commander to manage your files and folders, you've probably noticed the Wipe the content option available on the Delete window (that appears when you choose the Delete command from the menu of AB Commander):

Is (Wipe the content) the same as (Secure Delete)?

Secure delete