If centrifugal force did not exist, objects that are rotating would fly off in a straight line. For example, if you whirled a ball around on a string, the ball would fly away from you in a straight line. This is because there would be no force pulling the ball back towards you.
Similarly, if centrifugal force did not exist, objects in orbit would fly away from their central object in a straight line. This is because there would be no force causing them to move in a circular path.
In short, centrifugal force is essential for keeping objects rotating and in orbit.