An organ can mean anything from a lightweight electronic keyboard to a massive console pipe organ built into a room, and those two things need completely different plans. Figuring out which one you actually have is the first and most important step.
Pro tip: If you are unsure what kind of organ you have, take a photo and call a couple of piano or organ moving specialists for a quick assessment before you commit to a DIY plan.
Watch out: Never attempt a DIY move on a full console pipe or theater organ; these can weigh 300 to 600+ pounds with delicate internal amplifiers and speaker systems that specialty movers are trained to protect.