erasing old Macintosh HD hard drive

I have a MacBook Pro (13-inch, late 2011) running Mac OS 10.10. My hard drive crashed and I was not able to repair it using Disk Utility. I replaced the hard drive and installed from my Time Machine back up external drive. This seems to have fixed the problem. My question now is, how to I completely erase the old (broken) hard drive? I want to wipe it completely clean to get rid of all information on it. When I use a USB adapter to connect it to me MacBook Pro, I can access the files, but I can not erase the disk with Disk Utility. Any suggestions?

Why can you not erase that disk with disk utility ?

Cheers ... McBie

When I connect the old hard drive via the USB port and open Disk Utility, I only have the "First Aid" and "Partition" options. There is no option to "Erase", which is odd because I have the option to erase the new hard drive that I installed.

Ok, now that I take a closer look, I see on the left hand column of Disk Utility that there is a list of each drive and a subset of each partition. Is that correct? It seems I can erase the partition, but not the entire hard drive. Does that make sense?

You could create a new partition ( or delete the existing one ) , then format the disk and than securely erase.

Cheers ... McBie

Thanks for the help. It seems erasing the partition worked, I am now able to securely erase the entire drive.

No worries mate.

Cheers ... McBie