Hey there, Question22.
You are right that a simple format won't delete the data and should not be that hard to be recovered. This is because basically after you reformat a partition or a whole drive, the data is still intact (as long as you don't write anything over it). It's just that the file system has changed and the OS does not "see" the data because of that.
If you want to be sure that nothing will ever be recovered from that drive, you don't need to go and look for 3rd party software, as you could use WD's DLG (Data Lifeguard), which is WD's diagnostic tool, but it also supports low level format (a.k.a. Write Zeros). This basically overwrites each single sector of the drive with zero, making your files impossible to recover...