For instructions that would be actually useful, we'd need more information. You can remove any route using the "ip route delete" command, but if you don't set up a new default route, you won't be able to talk to anything that isn't on the same LAN as the machine whose route was deleted. That can be embarrassing when you've used ssh to login and do the work from somewhere else.
Loudly announcing something is true and finding out you're wrong makes you feel foolish.
Finding out you're wrong and refusing to admit it makes you LOOK foolish.
where default_gw_ip is the IP Address of the default gateway
You can also combine the above two steps using the single command
# ip route replace default via default_gw_ip
Please note that these changes will not be persistent across reboots
(or network service restarts). If you want to make the changes permanent,
you will have to change the default gateway settings either through the network configuration
tool provided by your distribution or in the network scripts.
# vi /etc/sysconfig/network