Cancelling Force of Rigidbody for new Direction

Hi I was hoping someone could tell me how I would go about causing an object to fly in a new direction immediately. Currently, I'm adding force to the Rigidbody, but this means that even after turning the object, the previously accumulated force remains. I know I should cancel this force, but I'm not sure what the best way of doing so would be.

Also, I HAVE managed to eliminate the force of my rotation, so that the object only rotates so long as a player is holding down the appropriate button. However, I'm not sure that the way I did it - manually providing a Vector3 (0, 0, 0), is the best way to do so. Can someone tell me whether there's a better way?

Thanks!

     public float speed = 10f;
     public float turnSpeed = 0.01f;
 
 
     private Rigidbody rBody;
     private float accel;
     private float acceleration = 10f;
     private float steer;
 
     // Use this for initialization
     void Start ()
     {
         rBody = GetComponent<Rigidbody> ();
     }
 
     // Update is called once per frame
     void Update ()
     {
         accel = Input.GetAxis ("Accel");
         steer = Input.GetAxis ("Steer");
 
     }
 
     void FixedUpdate ()
     {
         
         rBody.AddRelativeForce (0f, 0f, accel * acceleration);
         if (rBody.velocity.magnitude > speed)
             rBody.velocity = rBody.velocity.normalized * speed;
         if (steer == 0)
             rBody.angularVelocity = new Vector3 (0, 0, 0);
         else
             rBody.AddRelativeTorque (0f, steer * turnSpeed, 0f);
     }