If you want to do it I would suggest creating a floppy disk for when you want to restore your system in case the CDROM isn't recognised as a system disk.
Format a floppy disk with 'MSDOS startup disk'.
You might be able to restore straight from the CDROM, you could try setting the 1st Boot up device to CDROM in the bios and save (Usually Press Delete on restart to get into the bios) and then see if the Restore CD starts up. Should try this before formatting

I imagine the restore disk contains all the information you need for a restore. Backup any data not related to the operating system that you want on to other disks.
If you feel sure you can restore your system with the disks you have then to format simply boot up with the floppy disk or CDROM and enter the MSDOS mode and type: format c:\ or whatever drive it is that you want to format at dos prompt. Remember this will delete ALL data on the hard drive.
Incidently why do you want to format your drive?