How to make an object move without assigning a rigidbody to it

I have a gameobject that goes up and down by itself. The code is very simple

 void FixedUpdate ()
{
    rb.velocity = new Vector2(rb.velocity.x, dir);
    
    if (transform.position.y > start)
        dir = Mathf.Abs(dir) * -1;

    else if (transform.position.y < end)
        dir = Mathf.Abs(dir);
}

However, I don’t like the fact that it has a rigidbody, because I don’t want its movement to be affected when another object eventually collides with it. So would it be possible for the object to continue moving up and down by itself without a rigidbody?

EDIT

Thanks to MT369MT for the solution

I simply replaced

 rb.velocity = new Vector2(rb.velocity.x, dir);

with

  transform.Translate(Vector2.up * speed);

Hi,
Try using transform.Translate that doesn’t need a rigidbody.