Removing GRUB when I can’t boot to DOS

I have an old Pentium MMX with Windows 98, Windows 2000 SP4 and Linux (Mepis 3.3) partitions. I was using GRUB for the boot menu, which then step to the Windows boot menu.
I deleted the linux partitions with Windows Disk Management. Of course when I rebooted, I got a GRUB error 17.

I problem is that I can’t boot to this PC! I’ve tried boot floppies and CDs but GRUB always gets there first and fails:

Verifying DMI pool data…
GRUB loading Stage 1.5.

GRUB loading, please wait…
error 17

How do I workaround GRUB?
Alternatively, if I attach the HDD to another PC, I guess I could run fdisk /mbr from there, right?