GRUB2:删除老的启动菜单选项

升级完内核,启动菜单就会多一个老的kernel选项,想清除它们,就保留一个Ubuntu一个Windows就好了.一开始以为可以修改menu.ls,但是9.10下没有menu.lst了,grub.cfg也说明了不能改,后来发现其实不用走GRUB2设置这条路,直接删除old kernel就好了:
     Cleaning up older versions of Ubuntu kernel as well as merely from the GRUB2 menu by going to Synaptic Package Manager or Adept and search for 'linux-image'.