Set ppp0 for default route

Hello friends
I have a network configuration as follows

default via 188.x.x.192 dev ccinet0 proto static
188.x.x.0 / 24 dev ccinet0 proto kernel scope link src 188.x.x.191
192.168.1.0/24 dev br-lan proto kernel scope link src 192.168.1.1

And after connecting to vpn pptp and activating it, my ppp0 interface is activated and also ip route lk is as follows

default via 188.x.x.192 dev ccinet0 proto static
188.x.x.0 / 24 dev ccinet0 proto kernel scope link src 188.x.x.191
192.168.1.0/24 dev br-lan proto kernel scope link src 192.168.1.1
192.x.x.20 dev ppp0 proto kernel scope link src 192.x.x.180
ppp0      Link encap:Point-to-Point Protocol
          inet addr:192.x.x.180  P-t-P:192.x.x.20  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1360  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:88 (88.0 B)  TX bytes:70 (70.0 B)

Now I have to configure the route any way I want so that internet traffic passes through ppp0 by default and the vpn connection is lost

can guide me ? thanks