What Usage of no ip source-route?

I think ip source-route and policy routing very often get confused, but they are two very distinct things.

Policy routing is a way of specifying routes to depend on various parameters, including perhaps the source IP address of a packet. It is a local policy applied at a router.

ip source-route is something entirely different. It is a feature where the originator of an IP packet specifies, in that packet, which routers the packet must go through to reach its destination. The path is tagged onto the options field of the IP packet. The feature is very dangerous, and most NetAdmins disable it.

I think the confusion comes about because of the Words "source" and "route".