Insert the Windows 98 Startup disk'Floppy Disk" in the floppy disk drive, and then restart your computer.
When the Microsoft Windows 98 Startup menu is displayed, choose the Start computer without CD-ROM support option, and then press ENTER.
At a command prompt, type fdisk, and then press ENTER.
If the hard disk is larger than 512 MB, you receive the following prompt:
Your computer has a disk larger than 512 MB. This version of Windows includes improved support for large disks, resulting in more efficient use of disk space on large drives, and allowing disks over 2 GB to be formatted as a single drive.
This is from Microsoft but, you can use a floppy disk ISO written to a blank
CD.