Open the bi-fold door, and fold it flat against the wall to make it easier to handle. Kneel down on the floor on the hinge side. Locate the bottom height adjustment pivot, which sits on the floor bracket and looks like a screw with a white or clear plastic cover on it.
Ask another person to lift up on the door, which frees the bottom adjustment pivot from the floor bracket. Do not tilt the door that misaligns it; instead, lift it straight up.
Grasp the metal part of the adjustment mechanism in your hand. Turn it clockwise at least one to two turns.
Ask the other person to lower the door while you guide the metal section into the hole in the floor bracket.
Close the bi-fold door to determine if you raised it enough. If additional raising is required, repeat the process until the door opens and closes freely or the desired height is achieved.