You can quickly command an axis to its home position with HOME G28 (in the ZERO RETURN mode key row). If you type an axis letter and then press HOME G28 , the axis will rapid to its machine zero position. You can also press HOME G28 without an axis letter to send all axes to their machine zero positions.
Note that the doors must be closed for rapid motion to occur. Also be aware that rapid motion begins immediately when you press HOME G28 (there is no warning or confirmation message). Make sure the motion path is clear before you press HOME G28.