Low Level format hard drive

I have inherited a very tired compaq Armada 4131T laptop and I am trying to reformat the IBM 2G hard drive. I just can’t seem to get all the origional Compaq proprietary garbage off the boot sector so I can start fresh. There are a number of corrupt DOS files and writing over them (Command.com for example) doesn’t work. I should know this but I haven’t worked in DOS so long that I can’t remember how to do a Low Level format to clear all registers. What are the commands to get this done? Anyhelp will be appreciated