Can't delete backup folder

Two MAC’s one headache. I just purchased a OS X Mountain Lion and gave my wife my Snow Leopard. Passport did an automatic backup of the SL’s data. When I plugged it into my ML it also did a backup. I moved my wife’s backup to the trash since she won’t be using the WD. It’s now in the trash bucket on my ML and it won’t delete. It doesn’t show-up when I look at the drive and when I eject it the trash is empty. In short, how do I get rid of this thing?

Help!!  :confounded:

Hi, see if the following link helps.