本文出自 Suzf Blog。 如未注明，均为 SUZF.NET 原创。
1. the kernel that is being used in the system:
2. query system in all of the kernel:
#rpm -qa | grep kernel
3. remove the kernel you want to remove:
(eg, in my system, I want to delete the kernel of kernel-2.6.32-573.1.1.el6.x86_64, and I need to delete all the kernel-2.6.32-573.1.1.el6.x86_64's words.
#yum remove kernel-2.6.32-573.1.1.el6.x86_64
4. after the restart angd then you can see that the kernel was deleted, while the excess of the startup items are automatically deleted.
Manually modify the /etc/grub.conf to remove the extra items.