removing static route

#netstat -nr (shows the following with more static routes)
192.168.18.202 10.129.155.1 UGH 0 29 en0 - -
and i just want to remove the above one
i tried
#smitty rmroute
destination type= net
dest add = 192.168.18.202
default gateway= 10.129.155.1
net mask=255.255.255.0
but the message is

Before command completion, additional instructions may appear below.
Method error (/usr/lib/methods/chginet):
0514-009 Cannot delete an object from the device
configuration database.
0821-216 chginet: Cannot delete route (net,192.168.18.202,10.129.155.1) from CuA
t.
.......................................................................
i tried with the command
"route delete" also but not working
what to do??

just found this link in net. It might help you

Removing static route from TCPIP configuration - Toolbox for IT Groups