me@client:~$ sudo ip route show
Thu Jan 22 23:47:36 EST 2015
0.0.0.0/1 via 10.144.0.13 dev ppp0  proto none  metric 1
default via 192.168.1.1 dev eth0  proto static
10.144.0.1 dev ppp0  proto kernel  scope link  src 10.144.0.13
128.0.0.0/1 via 10.144.0.13 dev ppp0  proto none  metric 1
134.67.15.30 via 10.8.0.5 dev tun0  proto none  metric 1

me@client:~$ sudo ip route del 0.0.0.0/1 via 10.144.0.13
# note null response, so I'm assuming this worked. But ...

me@client:~$ date ; sudo ip route show
Thu Jan 22 23:47:54 EST 2015
# ... it's still there!
0.0.0.0/1 via 10.144.0.13 dev ppp0  proto none  metric 1
default via 192.168.1.1 dev eth0  proto static
10.144.0.1 dev ppp0  proto kernel  scope link  src 10.144.0.13
128.0.0.0/1 via 10.144.0.13 dev ppp0  proto none  metric 1
134.67.15.30 via 10.8.0.5 dev tun0  proto none  metric 1

# But if I `ip route del` a second time, ...
me@client:~$ sudo ip route del 0.0.0.0/1 via 10.144.0.13
# ... again null response, but ...

me@client:~$ date ; sudo ip route show
Thu Jan 22 23:48:13 EST 2015
default via 192.168.1.1 dev eth0  proto static
10.144.0.1 dev ppp0  proto kernel  scope link  src 10.144.0.13
128.0.0.0/1 via 10.144.0.13 dev ppp0  proto none  metric 1
134.67.15.30 via 10.8.0.5 dev tun0  proto none  metric 1
# ... now '0.0.0.0/1 via 10.144.0.13' is gone

me@client:~$ cat /etc/debian_version
jessie/sid
me@client:~$ uname -rv
3.11-2-amd64 #1 SMP Debian 3.11.8-1 (2013-11-13)