Are you suggesting that the corrupt partition/MBR is so because of a mechanical issue with the HDD (v. SW/OS issue)?
Regardless, if you just want to delete data on the disk, try Eraser
It is a free, open source app that I find extremely proficient. You can select from any of several levels of security erasing and even overwrite sectors with nonsensical data. Install and it will place an icon in the tray. Right-click the icon, open the app, from the tool bar click the down-arrow next to ERASE SCHEDULE, select NEW TASK, click on ADD DATA at the bottom of the window, and then you can select FILES, FILE IN FOLDER, UNUSED DISC SPACE, RECYCLE BIN and erase whatever you wish.
If you bought it from a reputable retailer, I should not think anyone would question the validity of your claim. If questions arise, I would simply tell the truth: I erased sensitive data.