If a valid static route exists it is always preferred over the default. You don't have to configure anything. That is simply the default behavior. The 'default' route is always the route of last resort.
If your static route isn't being use, this almost certainly means it isn't correct.
i am adding static route with wrong gateway
What are you trying to accomplish here? If a system detects and invalid route it is will continue to use the other entries in the route table.
If you are trying to null route a network send it to the loopback address or 0.0.0.0
, not some random valid, but inactive IP.