how to disable a NIC in centos

One liner? How about this as root?

echo "DEVICE=eth0" > /etc/sysconfig/network-scripts/ifcfg-eth0 && service network restart

It will remove the configuration for eth0 and replace it with something that is unconfigured.

In /etc/sysconfig/network-scripts/ifcfg-eth0 you need to have

ONBOOT=no

like MDMarra said but you also need to have

NM_CONTROLLED=no

or else the NetworkManager will boot the interface as it ignores the ONBOOT setting. Unless you don't use NetworkManager but I think it is common.

In /etc/sysconfig/network-scripts/ifcfg-eth0 you need to change ONBOOT= to no and you can delete the lines for IPADDR and NETMASK.

After you copy the config file, you need to restart the network daemon.