Hi
You have not said what operating system, i presume some version of windows
There are tools to wipe the mbr or begining of a hard disk
Example mbr wizard or western digital data life guard for windows
Mbr wizard should be able to change the signature so wiping the hdd should not be required
Both are on Hirens boot cd
If you have a new pc with win 8 or 10 you may have to disable secure boot in the bios / uefi to let Hirens boot cd start up
Regards
Mike Barnes
The main risk is writting to the wrong drive, so the good drive should be disconnected while operating on the other drive