I just had to do this with Lilo - try editing
with a text editor and remove Win98's entries (guessing it will be under "other" - just remove all lines until the next entry). At the top of lilo.conf there is a "default" entry - chaneg this to the name of your preferred regular OS.
Then open a console and type
- this should reconfigure lilo.
All this had to be done logged in as root, I am sure there's a better way but I'm literally a one-day-into-it newbie! I found this info scattered online and it worked though, don't be scared
Just keep a backup of lilo.conf in case it goes weird