root@ubuntu:/# apt-get remove --purge linux-386
Reading package lists... Done
Building dependency tree... Done
Package linux-386 is not installed, so not removed

ls from /boot:

root@ubuntu:/boot# ls
abi-2.6.15-26-k7     initrd.img-2.6.15-26-k7  vmlinuz-2.6.15-26-k7
config-2.6.15-26-k7  memtest86+.bin
grub                 System.map-2.6.15-26-k7