Two kernel.

Hi guys,i've update my system through yum .Then i reboot my system i saw two kernel.Iwant to remove one kernel line from grub.cong.Can i remove old kernel line.My grub.conf details:-

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You do not have a /boot partition. This means that
# all kernel and initrd paths are relative to /, eg.
# root (hd0,4)
# kernel /boot/vmlinuz-version ro root=/dev/sda5
# initrd /boot/initrd-version.img
#boot=/dev/sda
default=0
timeout=0
splashimage=(hd0,4)/boot/grub/image.xpm.gz
hiddenmenu
title Fedora Core (2.6.20-1.2948.fc6)
root (hd0,4)
kernel /boot/vmlinuz-2.6.20-1.2948.fc6 ro root=LABEL=/1 rhgb quiet
initrd /boot/initrd-2.6.20-1.2948.fc6.img
title Fedora Core (2.6.18-1.2798.fc6)
root (hd0,4)
kernel /boot/vmlinuz-2.6.18-1.2798.fc6 ro root=LABEL=/1 rhgb quiet
initrd /boot/initrd-2.6.18-1.2798.fc6.img
title Other
rootnoverify (hd0,1)
chainloader +1

can i do,its not a dangerous?
ThanX in Advance