Clean up old kernel in grub list (Ubuntu)

• check the current kernel 
  [] uname -a
  Linux coffee 2.6.32-27-generic #49-Ubuntu SMP ...
• [] cd boot
• [] ls vmlinuz-*
  vmlinuz-2.6.32-26-generic
• [] apt-get remove linux-image-2.6.32-26-generic

I didn't try to run apt-get autoremove,  but I don't know it works or not