grrrrr.. i need help

i asked a friend to help me install xp over win98 .. i
was in big hurry and should have just done a fresh
install but didnt have bootup disk for 98. So we
installed over 98 andit seems to be doing ok.. but today
i decided I wanted to do fresh install and in him helping
me do so we created another version of windows xp on my
computer.. all i need to know how to do is get rid of the
version i installed today.. how do i delete that
version?? please help.. im going to just go with the
upgraded version we did last night it seems to be working
well