How do you wipe out the hard drive on the mac book pro's

Are you talking about the MBP's internal drive or an external one?

To wipe out your internal hard drive : loosing everything (obviously noting that you will no longer be able to run os x unless you reinstall it) :

Insert the OS X install DVD that came with the computer. When its loaded restart the computer. When it starts to boot again hold down the C button so that the computer boots from the cd/dvd drive.

When its booted select your language, then choose UTILITIES and DISK UTILITY from the menu. When disk utility is loaded highlight the hard drive you want to erase and click on the erase tab. At this point you can click on the security options button if you want to zero out all the data on the disk (so that it cannot be recovered)

Now click on the Erase button (after closing the security options if you selected it) to wipe the disk. Please note that everything will be erased!!

If you close disk utility at this point you can continue to reinstall os x or just shutdown the computer.

Start up from Disc 1 of the MBP System discs and select Disk Utility from the menubar.