Do you mean that it flashes and beeps continuously or just regularly when you are driving?
In the first case the system needs technical attention from your dealer, in the second case it is just a question of adopting a more precise driving style.
Most of us found out how sloppy we had become with white lines over time when getting used to the car, but hardly ever hear a beep after a while.
The off-switch will reset itself to "on" after you switch off the car and not disable the system permanently, as it is a safety feature. I suppose that the best way to silence the system permanently is to stick a piece of duct-tape on your windscreen over the camera.