Make diferent sketches pressing one button

I am doing a robot car and I want to use my phone to control it by bluetooth, also I want to know if it's possible that if I press a button starts another sketch for example I am controling the robot, I press a button and the robot started to dodge object for it's own, Thank you very much

You can't really run different sketches but you can fairly easily have one sketch which does two different things depending on some condition, like a variable set by a button you pressed.