To uninstall Red Hat Linux from your system, you will need to remove the GRUB or LILO information from your master boot record (MBR).
In MS-DOS, Windows 95/98/Me you can use fdisk to create a new MBR with the undocumented flag /mbr. This will only rewrite the MBR to boot the primary DOS partition. The command should look like the following:
If you need to remove Linux from a hard drive, and have attempted to do this with the default MS-DOS fdisk, you will experience the Partitions exist but they do not exist problem. The best way to remove non-MS-DOS partitions is with a tool that understands partitions other than MS-DOS (such as Windows NT/2000/XP, which are not based on MS-DOS).
You can do this with the installation media by typing linux expert at the boot: prompt.
Select install (versus upgrade) and at the point when you should partition the drive, choose fdisk.
In fdisk, type p to print out the partition numbers and then remove the Linux partitions with the d command. When you are satisfied with the changes you have made, you can quit with a w and the changes will be saved to disk. If you deleted too much, type q and no changes will be made.
After you have removed the Linux partitions, you can reboot your computer using Control-Alt-Delete instead of continuing with the install.