Mac from University needs reformat

[Kongjirra]

Dad works at a Uni that was throwing out iMacs, he bought one home that he rescued. He'd like to reformat it and use it, but it has an automatic login screen and network setup. It possibly has an additional hard drive in it that it boots from that doesn't appear as a partition. I can't change the boot drive.
It doesn't seem like I can erase or reformat the additional drive. Is there a way to wipe and reformat the second-hand computer or is it unsalvagable? Maybe an external boot drive or boot disc?

 

[jerwin]

hold down option after the boot chime.

 

[DeltaMac]

Can you find out exactly which iMac you have?
If there is a firmware password on the iMac, then that needs to be cleared (if your Dad still wants to reformat the drive, that's the only solution)
Clearing a firmware password can be done with an easy trick of removing some of the RAM, and doing an NVRAM reset. But, that will not work if the iMac is newer than a 2010 model.
Or, your Dad can try to contact the IT folks at Uni, who (one would hope) can clear a firmware password (because they will know what that password is)
Apple can clear a firmware password on a newer iMac (newer than 2010 models), but your Dad would have to prove ownership with a receipt that Apple will accept (which may not happen)