Desinstalar kernel viejos

[David]

Hola Listeros:
Hace poco se me actualizó el kernel de mi Ubuntu 8.04.2 y en el menú del GRUB me encontré con múltiples kernels entre los que elegir para arrancar mi Ubuntu, para que no me mostrase tantas opciones al inicio comenté los Kernels más antiguos en menu.lts y ya no me los muestra. 
Ahora deseo desinstalar los kernel antiguos que no utilizo y que comenté en el menu.lts, para hacer esto me fui a Synantic pero éste no me muestra ningún kernel ni viejo ni nuevo, mi consulta es la siguiente, ¿cómo podría desinstalar los kernels viejos sin estropear los que me muestra el menú de GRUB?. 

Por si os sirve de algo, aquí teneis mi menu.lts

menu.lst - See: grub(8), info grub, update-grub(8)
#            grub-install(8), grub-floppy(8),
#            grub-md5-crypt, /usr/share/doc/grub
#            and /usr/share/doc/grub-doc/.

## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not use 'savedefault' or your
# array will desync and will not let you boot your system.
default        0

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout        10

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-25-generic
root        (hd0,2)
kernel        /vmlinuz-2.6.24-25-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
initrd        /initrd.img-2.6.24-25-generic
quiet

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-25-generic (recovery mode)
root        (hd0,2)
kernel        /vmlinuz-2.6.24-25-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
initrd        /initrd.img-2.6.24-25-generic

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic
root        (hd0,2)
kernel        /vmlinuz-2.6.24-24-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
initrd        /initrd.img-2.6.24-24-generic
quiet

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic (recovery mode)
root        (hd0,2)
kernel        /vmlinuz-2.6.24-24-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
initrd        /initrd.img-2.6.24-24-generic

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic
root        (hd0,2)
kernel        /vmlinuz-2.6.24-23-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
initrd        /initrd.img-2.6.24-23-generic
quiet

title        Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic (recovery mode)
root        (hd0,2)
kernel        /vmlinuz-2.6.24-23-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
initrd        /initrd.img-2.6.24-23-generic

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-22-generic
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-22-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
# initrd        /initrd.img-2.6.24-22-generic
# quiet

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-22-generic (recovery mode)
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-22-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
# initrd        /initrd.img-2.6.24-22-generic

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-21-generic
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-21-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
# initrd        /initrd.img-2.6.24-21-generic
# quiet

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-21-generic (recovery mode)
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-21-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
# initrd        /initrd.img-2.6.24-21-generic

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-19-generic
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-19-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro quiet splash
# initrd        /initrd.img-2.6.24-19-generic
# quiet

# title        Ubuntu 8.04.3 LTS, kernel 2.6.24-19-generic (recovery mode)
# root        (hd0,2)
# kernel        /vmlinuz-2.6.24-19-generic root=UUID=838a91b3-0754-405a-8005-2379df88d33a ro single
# initrd        /initrd.img-2.6.24-19-generic

title        Ubuntu 8.04.3 LTS, memtest86+
root        (hd0,2)
kernel        /memtest86+.bin
quiet

### END DEBIAN AUTOMAGIC KERNELS LIST

# This is a divider, added to separate the menu items below from the Debian
# ones.
title        Other operating systems:
root


# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/sda1
title        Microsoft Windows XP Professional
root        (hd0,0)
savedefault
makeactive
chainloader    +1