how to remove the network alias (ex: ifcfg-eth0:2)from RHEL5, i had deleted the ifcfg-eth0:2 file from /etc/sysconfig/network-scripts/ifcfg-eth0:3
but i can still see the entry in the graphical network configuration after i issued the command
system-config-network, i want to remove it from there. can any one help me please.

That removes the on-disk cfg; now issue
as root

Rather than restarting 'network', you could additionally remove '/etc/sysconfig/networking/devices/ifcfg-eth0:2'. At least on my test host (CentOS 5.4), after removing that file, the interface was no longer displayed from 'system-config-network'. If you also need / want to remove the configured interface, try:
where 10.0.23.172/23 is the IP_address and CIDR representation of the netmask in use ('/sbin/ip address show' can show IPAddr/CIDR). An example of dealing with logical interfaces can be seen here.

thanks chrism01 and troysunix so much for help, but really i tried your commands but still shows me the same problem finally i mix the commands together as follows and it works:

1- remove the ip address:
#ip address delete 192.168.0.102/24 dev eth0:2

2- remove the device:
#rm -f /etc/sysconfig/networking/devices/ifcfg-eth0:2

3- remove the file:
#rm -f /etc/sysconfig/network-scripts/ifcfg-eth0:2

then check the "system-config-network" command there is no eth0:2 any more.

thanks again i will not success with out your help.