Q: Got 1 cup of water in gas, used 3 ans dry gas, 2 days later car is knocking, my perminent damage is?

I doubt there is permanent damage, but you need to get the water out of there or there will be. The best way to get the water out is with the fuel pump. The water will settle in the bottom of the tank, which is where the pump is, so the way to get it out is to run the pump, probably using a scan tool, while the fuel line is disconnected and run to a catch can. Then you can fill the tank up, and pour in ONE can of fuel conditioner, no more. After driving through a few tanks of gas you will probably have the system purged of water.. You will likely need help with this because it will require equipment and know how most people don’t have. Contact YourMechanic to have a technician come to your home or office to check your knocking noise and let you know what can be done