how to cleanly remove the chroot environment?

[avishai <avishai.hendel@gmail.com>]

Hello all,

Following my recent finding that flash media can *finally* be played
on my iceweasel (and when I say finally, I mean: DAMN, that took a
long time), i see no need to have an extra 32bit system installed. So
I'm thinking about removing it completely, however a bit of googling
on it beforehand led me to this:

 "Be VERY careful if you decide to remove the chroot at some point in
the future. Any filesystems you have mounted with bind MUST be
unmounted before you rm -f the chroot. If you fail to do this you'll
remove your valuable data (/me sniff's and wipes away a tear) "
http://www.debian-administration.org/articles/356

Anyone care to explain this one to me before I throw away all that
"valuable data"?
Cheers,
Avishai.

some extra data:
$ mount
/dev/sda2 on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
procbususb on /proc/bus/usb type usbfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
none on /sys/fs/fuse/connections type fusectl (rw)
/dev/sda1 on /mnt/xp type ntfs (ro,uid=1000)
/dev/hdc1 on /home/avishai/storage type fuse
(rw,nosuid,nodev,noatime,allow_other)
/home on /var/chroot/sid-ia32/home type none (rw,bind)
/tmp on /var/chroot/sid-ia32/tmp type none (rw,bind)
/dev on /var/chroot/sid-ia32/dev type none (rw,bind)
/proc on /var/chroot/sid-ia32/proc type none (rw,bind)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

$ cat /etc/fstab # from normal 64bit root
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
/dev/sda2       /               ext3    defaults,errors=remount-ro
0       1
/dev/sda5       none            swap    sw              0       0
/dev/hda        /media/cdrom0   iso9660 ro,user,noauto  0       0
/dev/sda1       /mnt/xp         ntfs    ro,uid=avishai  0       0
/dev/hdc1       /home/avishai/storage   ntfs-3g uid=avishai
0       0

# sid32 chroot
/home   /var/chroot/sid-ia32/home none    bind      0       0
/tmp    /var/chroot/sid-ia32/tmp  none    bind      0       0
/dev    /var/chroot/sid-ia32/dev  none    bind      0       0
/proc   /var/chroot/sid-ia32/proc none    bind      0       0

... and /var/chroot/sid-ia32/etc/fstab looks exactly the same.