The MoveObjects cheat opens up the ability to raise objects up or lower them back down to their starting height. On PC/Mac, move an object up with the number 9 key until it is at the height you want. To lower it back down, press the number 0 key. For console players, press L2 + R2 (PlayStation) or both triggers (Xbox) simultaneously with an object selected and use the up and down directional buttons to raise or lower the object as needed.