An ESC is an Electronic Speed Controller. It's purpose is to control the speed and direction of a Brushless DC Motor.
A Bushless DC Motor ("BLDM") is not like other motors. You can't just provide it power and it will spin. Instead it is made up of three (or multiples of three) electromagnets along with a permanent magnet on the rotor. Energising these ...
Basically you can't. PWM value required to turn to a specific degree will depend on motors, on voltage, on hardware, in the current velocity of the car and probably on the surface under the wheel. Also keep in mind that real cars don't turn like that (at a fixed angle). Instead, driver constantly adjusts the position of the steering wheel, while looking at ...
You've got two possibilities:
You can't have full off in "non-inverting PWM" mode
You can't have full on in "inverting PWM" mode
In the Arduino core it's solved by turning off the PWM output and setting logical 0 or 1 for corner values.
And if you need full off but you don't need full on, you can use inverted PWM mode.